Copolymers of ethylene with α-olefins

ABSTRACT

Copolymers of ethylene with α-olefins which have a molar mass distribution M w /M n  of from 1 to 8, a density of from 0.85 to 0.94 g/cm 3 , a molar mass M n  of from 10.000 g/mol to 4 000 000 g/mol and a CDBI of less than 50% and in which the side chain branching of the maxima of the individual peaks of the short chain branching distribution is in each case greater than 5 CH 3 /1 000 carbon atoms, a process for preparing them, a catalyst suitable for preparing them and fibers, moldings, films or polymer mixtures in which these copolymers are present.

This application is the U.S. national phase of International ApplicationPCT/EP2003/014437, filed Dec. 18, 2003, claiming priority to GermanPatent Application 10261252.8 filed Dec. 20, 2002, and the benefit under35 U.S.C. 119(e) of U.S. Provisional Application No. 60/451,836, filedMar. 4, 2003; the disclosures of International ApplicationPCT/EP2003/014437, German Patent Application 10261252.8 and U.S.Provisional Application No. 60/451,836, each as filed, are incorporatedherein by reference.

The present invention relates to copolymers of ethylene with α-olefinswhich have a molar mass distribution M_(w)/M_(n) of from 1 to 8, adensity of from 0.85 to 0.94 g/cm³, a molar mass M_(n) of from 10 000g/mol to 4 000 000 g/mol and a CDBI of less than 50% and in which theside chain branching of the maxima of the individual peaks of the sidechain branching distribution is in each case greater than 5 CH₃/1 000carbon atoms, to a process for preparing them and to fibers, moldings,films or polymer mixtures in which these copolymers are present.

Copolymers of ethylene with higher α-olefins such as propene, 1-butene,1-pentene, 1-hexene or 1-octene, known as LLDPE (linear low densitypolyethylene), can be prepared, for example, using classicalZiegler-Natta catalysts based on titanium or else by means ofmetallocenes. Since these ethylene copolymers do not consist of manyequal-length chains but have a molar mass distribution comprisingrelatively long and relatively short polymer chains, the incorporationof the comonomer into the chains of various lengths may be the same ordifferent. The number of side chains formed by incorporation of thecomonomer and their distribution, known as the short chain branchingdistribution SCBD, is very different when different catalyst systems areused. The number and distribution of the side chains has a criticalinfluence on the crystallization behavior of the ethylene copolymers.While the flow properties and thus the processing of these ethylenecopolymers depends mainly on their molar mass and molar massdistribution, the mechanical properties are highly dependent on theshort chain branching distribution. The short chain branchingdistribution also places a role in particular processing methods, e.g.in film extrusion where the crystallization properties of the ethylenecopolymers during cooling of the extruded film is an important factor indetermining the speed with which a film can be extruded and theresulting film quality.

There are various methods of determining the short chain branchingdistribution. One method is the “analytical temperature rising elutionfractionation technique” (TREF). Here, the polymer is slowlycrystallized from a polymer solution onto an inert support material bycooling and Is subsequently eluted at various temperatures. Theconcentration of polymer In the fractions obtained at varioustemperatures is measured by means of infrared spectroscopy. At lowtemperatures, molecules having a large number of side chains are eluted.As the temperature increases, the less branched polymer fractions arealso eluted. The concentration of the polymer solutions obtained isplotted against the elution temperature so as to obtain the short chainbranching distribution. The TREF result can also be calibrated by meansof preparatively isolated polyethylene fractions having a defined numberof short chain branches. The number of the side chains is usuallyreported as methyl groups per 1 000 carbon atoms of the polymer chains(CH₃/1 000C) and thus includes the end groups and any long chainbranches formed in the polymerization. The TREF method is described, forexample, in Wild, Advances in Polymer Science, 98, p. 1-47, 57 p. 153,1992. From the TREF, it is possible to determine, for example, the CDBI(composition distribution breadth index), which is a measure of thebreadth of the distribution of the composition. This is described, forexample, in WO 93/03093. The CDBI is defined as the percent by weight ofthe copolymer molecules having a comonomer content of ±25% of the meanmolar total comonomer content.

A new method of determining the short chain branching distribution,namely Crystaf®, has recently been developed, since the TREF method isvery time-consuming. Here, the short chain branching is determined in asingle step during the process of crystallization from the polymersolution. The polymer solution is stirred, slowly cooled and a sample ofthe solution is taken at particular temperatures. These samples containthe polymer fractions which have not yet crystallized and theirconcentration is determined by means of Infrared spectroscopy. Since thesamples are taken during the crystallization process, a cumulative shortchain branching distribution is obtained. Subtraction enables a shortchain branching distribution similar to that obtained from TREF to beobtained. Apart from rapid measurement of data, the Crystaf® methodoffers the additional advantage that the soluble or uncrystallizablepolymer components can also be determined by this means (Monrabal B.;Crystallization analysis fractionation, a new technique for the analysisof branching distribution in polyolefines; J. appl. Polym. Sci.1994;52;491-9).

Ziegler-Natta catalysts give LLDPE having a broad or bimodal short chainbranching distribution and a relatively broad mean molar massdistribution M_(W)/M_(n) which is usually greater than 5, where M_(n) isthe number average molar mass and M_(W) is the weight average molarmass. The side chain branching is usually more pronounced in the polymerchains having a relatively low molar mass than in those having highermolar masses. Furthermore, these copolymers contain a high molecularweight polymer fraction having an extremely small proportion of sidechain branches of less than 4CH₃/1 000 carbon atoms.

In contrast, use of metallocene catalysts in the polymerization usuallygives ethylene copolymers having a narrow molar mass distribution and aCDBI of >50%. These LLDPEs have particularly advantageous mechanicalproperties. The short chain branching distribution is monomodal.Copolymerization with higher α-olefins often leads to a reducedmolecular weight. In general, chain termination becomes increasinglyfavored at higher comonomer concentrations and the molecular weight isthus reduced (U.S. Pat. No. 5,625,016 states that M_(n) is smaller thanabout 50 000). The low molecular weight copolymers can lead, firstly, todeposits in the reactor during the polymerization and, secondly, toundesirable product properties such as sticky surfaces. LLDPEs having ahigh molecular weight and a high comonomer content are difficult toproduce.

WO 01/92346 discloses cyclopentadienyl complexes of groups 4-6 of thePeriodic Table of the Elements in which a dihydrocarbyl-Y group, where Yis an element of group 14 of the Periodic Table of the Elements bearingparticular Lewis bases, is bound to the cyclopentadienyl system.

WO-A-98/44011 describes ethylene copolymers with at least onealpha-olefin having at least 5 carbon atoms which have a melt index MIof from 0.1 to 15, a CDBI of at least 70%, a density of from 0.91 to0.93 g/ml, a haze value of less than 20%, a melt index ratio MIR of from35 to 80, a mean modulus of from 20 000 to 60 000 psi and a definedratio of modulus to dart impact strength. Furthermore, the resultingpolymers are said to have essentially no unsaturated end groups.

WO-A-93/12151 describes ethylene copolymers with alpha-olefins having atleast 10 carbon atoms which have a density of from 0.85 to 0.95 g/cm³, amean molecular weight M_(W) of from 30 000 to 1 000 000 dalton and amolecular weight distribution in the range from 2 to 4.

It has now been found that ethylene copolymers having an at leastbimodal short chain branching distribution and at the same time a narrowmolar mass distribution and a particularly good dart drop impactstrength are obtained when the polymerization is carried out usingparticular chromium catalysts.

We have accordingly found copolymers of ethylene with α-olefins whichhave a molar mass distribution M_(W)/M_(n) of from 1 to 8, a density offrom 0.85 to 0.94 g/cm³, a molar mass M_(n) of from 10 000 g/mol to 4000 000 g/mol, a CDBI of less than 50% and in which the side chainbranching of the maxima of the individual peaks of the short chainbranching distribution is in each case greater than 5 CH₃/1 000 carbonatoms.

Furthermore, we have found a process for preparing the ethylenecopolymers of the present invention, which comprises polymerizingethylene with α-olefins in the presence of the following components:

-   A) at least one monocyclopentadienyl complex comprising the    structural feature of the formula (Cp-Z-A)Cr (I), where the    variables have the following meanings:    -   CP-Z-A is a ligand of the formula (II)

-   -   where    -   R^(1A)-R^(4A) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from        1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in        the aryl part, NR^(11A) ₂, N(SiR^(11A) ₃)₂, OR^(11A), OSiR^(11A)        ₃, SiR^(11A) ₃, BR^(11A) ₂, where the organic radicals        R^(1A)-R^(4A) may also be substituted by halogens and where at        least two of the vicinal radicals R^(1A)-R^(4A) are joined to        form a five- or six-membered ring, and/or two vicinal radicals        R^(1A)-R^(4A) are joined to form a heterocycle which contains at        least one atom from the group consisting of N, P, O and S,    -   Z is a bridge between A and Cp having the formula

-   -    where        -   L is carbon or silicon, preferably carbon,        -   R^(5A),R^(6A) are each hydrogen, C₁-C₂₀-alkyl,            C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10            carbon atoms in the alkyl part and 6-20 carbon atoms in the            aryl part or SiR^(11A) ₃, where the organic radicals R^(5A)            and R^(6A) may also be substituted by halogens and R^(5A)            and R^(6A) may also be joined to form a five- or            six-membered ring,    -   A is

-   -   where    -   E^(1A)-E^(4A) are each carbon or nitrogen,    -   R^(7A)-R^(10A) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from        1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in        the aryl part or SiR^(11A) ₃, where the organic radicals        R^(7A)-R^(10A) may also bear halogens or nitrogen or further        C₁-C₂₀-alkyl groups, C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups,        alkylaryl groups having from 1 to 10 carbon atoms in the alkyl        part and 6-20 carbon atoms in the aryl part or SiR^(11A) ₃as        substituents and two vicinal radicals R^(7A)-R^(10A) or R^(7A)        and Z may also be joined to form a five- or six-membered ring,    -   R^(11A) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from        1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in        the aryl part and two geminal radicals R^(11A) may also be        joined to form a five- or six-membered ring and    -   p is 0 when E^(1A)-E^(4A) is nitrogen and is 1 when        E^(1A)-E^(4A) is carbon,

-   B) optionally an organic or inorganic support,

-   C) optionally one or more activating compounds and

-   D) optionally one or more metal compounds containing a metal of    group 1, 2 or 13 of the Periodic Table.

Furthermore, we have found polymer mixtures in which at least onecopolymer of ethylene with C₃-C₁₂-α-Olefins according to the presentinvention is present and also fibers, films and moldings in which thecopolymers of ethylene with C₃-C₁₂-α-olefins according to the presentinvention are present as significant component.

We have also found the use of the copolymers of ethylene withC₃-C₁₂-α-olefins of the present invention for producing fibers, filmsand moldings.

Preferred copolymers of ethylene with α-olefins are those which have amolar mass distribution M_(W)/M_(n) of from 1 to 8, a density of from0.85 to 0.94 g/cm³, a molar mass M_(n) of from 10 000 g/mol to 4 000 000g/mol and an at least bimodal short chain branching distribution and inwhich the side chain branching of the maxima of the individual peaks ofthe short chain branching distribution is in each case greater than 5CH₃/1 000 carbon atoms.

Particular preference is given to copolymers of ethylene with α-olefinswhich have a molar mass distribution M_(w)/M_(n) of from 1 to 8, adensity of from 0.85 to 0.94 g/cm³, a molar mass M_(n) of from 10 000g/mol to 4 000 000 g/mol, a CDBI of less than 50% and an at leastbimodal short chain branching distribution and in which the side chainbranching of the maxima of the individual peaks of the short chainbranching distribution is in each case greater than 5 CH₃/1 000 carbonatoms.

The copolymer of ethylene with C₃-C₁₂-α-olefins of the present inventionhas a molar mass distribution M_(w)/M_(n) of from 1 to 8, preferablyfrom 1.5 to 5 and particularly preferably from 2 to 3.5. Its density isIn the range from 0.85 to 0.94 g/cm³, preferably from 0.86 to 0.93 g/cm³and particularly preferably from 0.87 to 0.91 g/cm³. The molar massM_(n) of the ethylene copolymers of the present invention is in therange from 10 000 g/mol to 4 000 000 g/mol, preferably from 50 000 g/molto 1 000 000 g/mol and particularly preferably from 100 000 g/mol to 400000 g/mol.

For the purposes of the present patent application, a monomodal shortchain branching distribution means that the short chain branchingdistribution determined by the Crystaf® method displays a singlemaximum. A bimodal short chain branching distribution means, for thepurposes of the present patent application, that the short chainbranching distribution determined by the Crystaf® method has at leasttwo points of inflection on a flank of a maximum. For the purposes ofthe present patent application, an at least bimodal short chainbranching distribution is one which may be bimodal, trimodal, etc., ormultimodal. The short chain branching distribution is preferably bimodalor trimodal, in particular bimodal.

The side chain branching of the maxima of the individual peaks of theshort chain branching distribution is in each case greater than 5 CH₃/1000 carbon atoms, preferably greater than 8 CH₃/1 000 carbon atoms, andis preferably in the range from 10 to 80 CH₃/1 000 carbon atoms andparticularly preferably from 15 to 60 CH₃/1 000 carbon atoms.

According to the present invention, the short chain branchingdistribution and the number of side chains is determined by means of theCrystaf® method. The elution temperatures obtained in this way areconverted by means of the reference table into the number of CH₃ groupsper 1 000 carbon atoms.

The molar mass distribution within the short chain branchingdistribution is preferably such that the fractions which form the peakhaving the highest number of CH₃/1 000 carbon atoms have a mean molarmass which is equal to or higher than that of the peak(s) having a lowernumber of CH₃/1 000 carbon atoms.

The peak having the highest number preferably has at least 8, preferablyat least 12 and particularly preferably at least 15, CH₃/1 000 carbonatoms more than the peak having the smallest number of CH₃/1 000 carbonatoms.

The ethylene copolymer of the present invention preferably has no peakin the Crystaf® spectrum of the differential distribution above 80° C.,preferentially not above 75° C. When used in film applications theethylene copolymers therefore show increased dart drop impact valuesand/or tensile yield and/or Elemendorf tear resistance. When used inheat sealable films the resulting films show low sealing temperaturesbut excellent mechanics of seal. When used as blend compositions theresulting blends show higher clarity and permeability compared to blendswith conventional ethylene copolymers.

The ethylene copolymer of the present invention preferably has at leastone peak in the Crystaf® spectrum of the differential distribution inthe range from 5 to 40° C. and at least one further peak in the Crystaf®spectrum of the differential distribution in the range from 25 to 80°C., preferably at least one peak in the Crystaf® spectrum of thedifferential distribution in the range from 8 to 30° C. and at least onefurther peak in the Crystaf® spectrum of the differential distributionin the range from 28 to 60° C.

The HLMFR of the ethylene copolymers of the present invention is in therange from 0.001 to 200 g/10 min, preferably from 0.1 to 50 g/10 min andespecially preferable from 2 to 40 g/10 min. For the purpose of thepresent invention, the expression “HLMFR” refers to the “high load meltflow rate” and is determined in accordance with ISO 1133 at 190° C.under a load of 21.6 kg (190° C./21.6 kg).

The ethylene copolymers of the present invention have preferably a longchain branching (lcb) rate λ (lambda) from 0 to 0.1 lcb/1000 carbonatoms, preferably from 0.001 to 0.09 lcb/1000 carbon atoms as measuredby light scattering as described in ACS Series 521, 1993, Chromatographyof Polymers, Ed. Theodore Provder; Simon Pang and Alfred Rudin:Size-Exclusion Chromatographic Assessment of Long-Chain Branch Frequencyin Polyethylenes, page 254-269. Films made with these ethylenecopolymers therefore show high bubble stability during film processing.

The ethylene copolymers of the present invention have preferably a highvinyl group content. The vinyl group content is preferably higher than0.05 vinyl groups/1000 carbon atoms, preferably from 0.1 to 1 vinylgroups/1000 carbon atoms and preferentially from 0.15 to 0.5 vinylgroups/1000 carbon atoms. Vinyl groups in this context refers to vinylgroups only and does not for example include vinylidene groups. Theethylene copolymers of the present invention have preferably a vinylidengroup content/1000 carbon atoms, which is higher than 0.1 vinylidengroups/1000 carbon atoms, preferably from 0.1 to 1.5 vinylidengroups/1000 carbon atoms and preferentially from 0.15 to 0.8 vinylidengroups/1000 carbon atoms. The total of vinyl and vinyliden groups ispreferably higher than 0.2 groups/1000 carbon atoms, preferably from 0.2to 2 groups/1000 carbon atoms and preferentially from 0.3 to 1groups/1000 carbon atoms. Vinyl groups usually are associated with apolymer chain termination after an ethylene insertion, whereasvinylidene groups are thought to occur if the polymer chain isterminated after comonomer insertion, like for example hexene insertion.Vinyliden and vinyl groups can be reacted with a functionalisationreagent or used for cross linking. The ethylene copolymers of thepresent invention are therefore very suitable for grafting, crosslinking and functionalisation.

In a preferred embodiment of the present invention, the copolymer has anindex of the breadth of the composition distribution of the comonomer ofless than 50%, in particular from 5 to 45% and particularly preferablyfrom 20 to 30%.

As comonomers which may be present, either individually or in admixturewith one another, in addition to ethylene in the copolymer of thepresent invention, it is possible to use all α-olefins having from 3 to12 carbon atoms, e.g. propene, 1-butene, 1-pentene, 1-hexene,4-methyl-1-pentene, 1-heptene, 1-octene and 1-decene. The ethylenecopolymer preferably contains, as comonomer units, copolymerizedα-olefins having from 3 to 9 carbon atoms, e.g. butene, pentene, hexene,4-methylpentene or octene. Particular preference is given to usingα-olefins selected from the group consisting of propene, 1butene,1-hexene and 1-octene. The comonomers are generally present incopolymerized form in the ethylene copolymer of the present invention inamounts of from 1 to 40% by weight, preferably from 2 to 30% by weightand in particular from 2 to 20% by weight, in each case based on theethylene copolymer.

The ethylene copolymers can, in particular, be prepared by means of theabove-described novel process using the substituted monoindenylchromiumcomplexes of the formula I.

The monocyclopentadienyl complexes A) used in the process of the presentinvention comprise the structural element of the formula (Cp-Z-A)_(m)Cr(I), where the variables are as defined above. The further ligands cantherefore be bound to the metal atom Cr. The number of further ligandsdepends, for example, on the oxidation state of the metal atom. Possiblefurther ligands do not include further cyclopentadienyl systems.Suitable further ligands are monoanionic and dianionic ligands as aredescribed, for example, for X. In addition, Lewis bases such as amines,ethers, ketones, aldehydes, esters, sulfides or phosphines can also bebound to the metal center Cr.

The polymerization behavior of the metal complexes can likewise beinfluenced by variation of the substituents R^(1A)-R^(4A). The numberand type of substituents can influence the ability of the olefins to bepolymerized to gain access to the metal atom M. This makes it possibleto modify the activity and selectivity of the catalyst In respect ofvarious monomers, in particular bulky monomers. Since the substituentscan also influence the rate of termination reactions of the growingpolymer chain, the molecular weight of the polymers formed can also bealtered in this way. The chemical structure of the substituents R^(1A)to R^(4A) can therefore be varied within a wide range in order toachieve the desired results and to obtain a tailored catalyst systemwith the proviso that at least two of the vicinal radicals R^(1A)-R^(4A)are joined to form a five- or six-membered ring, and/or two vicinalradicals R^(1A)-R^(4A) are Joined to form a heterocycle which containsat least one atom from the group consisting of N, P, O and S. Possiblecarboorganic substituents R^(1A)-R^(4A) are, for example, the following:C₁-C₂₀-alkyl which may be linear or branched, e.g. methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5- to 7-memberedcycloalkyl which may in turn bear a C₆-C₁₀-aryl group as substituent,e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclononyl or cyclododecyl, C₂-C₂₀-alkenyl, which may belinear, cyclic or branched and in which the double bond can be internalor terminal, e.g. vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl,hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl or cyclooctadienyl,C₆-C₂₀-aryl which may bear further alkyl groups as substituents, e.g.phenyl, naphthyl, biphenyl, anthranyl, o-, m-, p-methylphenyl, 2,3-,2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6-or 3,4,5-trimethylphenyl, or arylalkyl which may bear further alkylgroups as substituents, e.g. benzyl, o-, m-, p-methylbenzyl, 1- or2-ethylphenyl, where the organic radicals R^(1A)-R^(4A) may also besubstituted by halogens such as fluorine, chlorine or bromine.Furthermore, R^(1A)-R^(4A) may also be amino or alkoxy, for exampledimethylamino, N-pyrrolidinyl, picolinyl, methoxy, ethoxy or isopropoxy.In organosilicon substituents SiR^(11A) ₃, R^(11A) may be the samecarboorganic radicals as described in more detail in this paragraph forR^(1A)-R^(4A), with two R^(11A) also being able to be joined to form a5- or 6-membered ring, e.g. trimethylsilyl, triethylsilyl,butyldimethylsilyl, tributylsilyl, tri-tert-butylsilyl, triallylsilyl,triphenylsilyl or dimethylphenylsilyl. These SiR^(11A) ₃ radicals mayalso be bound to the cyclopentadienyl skeleton via an oxygen or nitrogenatom, for example trimethylsilyloxy, triethylsilyloxy,butyldimethylsilyloxy, tributylsilyloxy or tri-tert-butylsilyloxy.Preferred radicals R^(1A)-R^(4A) are hydrogen, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, vinyl, allyl, benzyl, phenyl, ortho-dialkyl- orortho-dichloro-substituted phenyls, trialkyl or trichloro-substitutedphenyls, naphthyl, biphenyl and anthranyl. As organosiliconsubstituents, particular preference is given to trialkylsilyl groupshaving from 1 to 10 carbon atoms in the alkyl radical, in particulartrimethylsilyl groups.

At least two of the vicinal radicals R^(1A)-R^(4A) are joined to form afive- or six-membered ring, and/or two vicinal radicals R^(1A)-R^(4A)are joined to form a heterocycle which contains at least one atom fromthe group consisting of N, P, O and S. Two vicinal radicalsR^(1A)-R^(4A) can, for example, in each case together with the carbonatoms bearing them, form a heterocycle, preferably a heteroaromatic,which contains at least one atom from the group consisting of nitrogen,phosphorus, oxygen and sulfur, particularly preferably nitrogen and/orsulfur. Preference is given to heterocycles and heteroaromatics having aring size of 5 or 6 ring atoms. Examples of 5-membered heterocycles,which may contain from one to three nitrogen atoms and/or a sulfur oroxygen atom as ring atoms in addition to carbon atoms, are1,2-dihydrofuran, furan, thiophene, pyrrole, isoxazole, 3-isothiazole,pyrazole, oxazole, thiazole, imidazole. Examples of 6-memberedheteroaryl groups, which may contain from one to four nitrogen atomsand/or a phosphorus atom, are pyridine, phosphabenzene, pyridazine,pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4triazine and 1,2,3-triazine.The 5- and 6-membered heterocycles may also be substituted byC₁-C₁₀-alkyl, C₆-C₁₀-aryl, alkylaryl having from 1 to 10 carbon atoms Inthe alkyl part and 6-10 carbon atoms in the aryl part, trialkylsilyl orhalogens such as fluorine, chlorine or bromine, dialkylamide,alkylarylamide, diarylamide, alkoxy or aryloxy or be fused with one ormore aromatics or heteroaromatics. Examples of the benzo-fused5-membered heteroaryl groups are indole, indazole, benzofuran,benzothiophene, benzothiazole, benzoxazole and benzimidazole. Examplesof benzo-fused 6-membered heteroaryl groups are chroman, benzopyran,quinoline, isoquinoline, cinnoline, phthalazine, quinazoline,quinoxaline, 1,10-phenanthroline and quinolizine. Naming and numberingof the heterocycles has been taken from Lettau, Chemie der Heterocyclen,1st edition, VEB, Weinheim 1979. The are preferably fused with thecyclopentadienyl skeleton via a C—C double bond of theheterocycle/heteroaromatic. Heterocycles/heteroaromatics containing aheteroatom are preferably 2,3- or b-fused.

Examples of cyclopentadienyl systems Cp having a fused heterocycle arethiapentalene, 2-methylthiapentalene, 2-ethylthiapentalene,2-isopropylthiapentalene, 2-n-butylthiapentalene,2-tert-butylthiapentalene, 2-trimethylsilylthiapentalene,2-phenylthiapentalene, 2-naphthylthiapentalene, 3-methylthiopentalene,4-phenyl-2,6dimethyl-1-thiapentalene,4-phenyl-2,6-diethyl-1-thiapentalene,4-phenyl-2,6-diisopropyl-1-thiapentalene,4-phenyl-2,6-di-n-butyl-1-thiapentalene,4-phenyl-2,6-di(trimethylsilyl)-1-thiapentalene, azapentalene,2-methylazapentalene, 2-ethylazapentalene, 2-isopropylazapentalene,2-n-butylazapentalene, 2-trimethylsilylazapentalene,2-phenylazapentalene, 2-naphthylazapentalene,1-phenyl-2,5-dimethyl-1-azapentalene,1-phenyl-2,5-diethyl-1-azapentalene,1-phenyl-2,5-di-tert-butyl-1-azapentalene,1-phenyl-2,5-di(trimethysilyl)-1-azapentalene,1-tert-butyl-2,5-dimethyl-1-azapentalene, oxapentalene,phosphapentalene, 1-phenyl-2,5-dimethyl-1-phosphapentalene,1-phenyl-2,5-diethyl-1-phosphapentalene,1-phenyl-2,5-di-n-butyl-1-phosphapentalene,1-phenyl-2,5-di-tert-butyl-1-phosphapentalene,1-phenyl-2,5-di(trimethylsilyl)-1-phosphapentalene,1-methyl-2,5-dimethyl-1-phosphapentalene,1-tert-butyl-2,5-dimethyl-1-phosphapentalene,7-cyclopenta[1,2]thieno[3,4]cyclopentadiene or7-cyclopenta[1,2]pyrrolo[3,4]cyclopentadiene.

In further preferred cyclopentadienyl systems Cp, the four radicalsR^(1A)-R^(4A), i.e. two pairs of vicinal radicals, form twoheterocycles, in particular heteroaromatics. The heterocyclic systemsare the same as those described in more detail above. Examples ofcyclopentadienyl systems Cp having two fused-on heterocycles are7-cyclopentadithiophene, 7-cyclopentadipyrrole or7-cyclopentadiphosphole.

The synthesis of such cyclopentadienyl systems having a fused-onheterocycle is described, for example, in the abovementioned WO98/22486. In “metalorganic catalysts for synthesis and polymerization”,Springer Verlag 1999, p. 150 ff, Ewen et al. describe further synthesesof these cyclopentadienyl systems.

Preference is also given to compounds in which two vicinal radicalsR^(1A)-R^(4A), in particular R^(1A) together with R^(2A) and/or R^(3A)together with R^(4A), form a fused ring system, in particular a C₆ ringsystem, particularly preferably an aromatic C₆ ring system, i.e.together with the cyclopentadienyl C₅ ring form, for example, anunsubstituted or substituted indenyl, benzindenyl, phenanthrenyl,fluorenyl or tetrahydroindenyl system, e.g. indenyl, 2-methylindenyl,2-ethylindenyl, 2-isopropylindenyl, 3-methylindenyl, benzindenyl or2-methylbenzindenyl. In particular, R^(1A) and R^(2A) together with thecyclopentadienyl system form a substituted or unsubstituted indenylsystem.

The fused ring system may bear a further C₁-C₂₀-alkyl groups,C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups, alkylaryl groups having from1 to 10 carbon atoms In the alkyl part and 6-20 carbon atoms in the arylpart, NR^(11A) ₂, N(SiR^(11A) ₃)₂, OR^(11A), OSiR^(11A) ₃ or SiR^(11A)₃, e.g. 4-methylindenyl, 4-ethylindenyl, 4-isopropylindenyl,5-methylindenyl, 4-phenylindenyl, 5-methyl-4-phenylindenyl,2-methyl-4-phenylindenyl or 4-naphthylindenyl.

As in the case of metallocenes, the monocyclopentadienyl complexes A)may be chiral. Thus, one of the substituents R^(1A)-R^(4A) of thecyclopentadienyl skeleton can have one or more chiral centers, or elsethe cyclopentadienyl system Cp can itself be enantiotopic, so thatchirality is induced only when the cyclopentadienyl system is bound tothe transition metal M (for formalisms regarding chirality incyclopentadienyl compounds, cf. R. Halterman, Chem. Rev. 92, (1992),965-994).

Possible carboorganic substituents R^(5A)-R^(6A) on the link Z are, forexample, the following: hydrogen, C₁-C₂₀-alkyl which may be linear orbranched, e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl orn-dodecyl, 5- to 7-membered cycloalkyl which may in turn bear aC₆-C₁₀-aryl group as substituent, e.g. cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl orcyclododecyl, C₂-C₂₀-alkenyl which may be linear, cyclic or branched andin which the double bond may be internal or terminal, e.g. vinyl,1-allyl, 2-allyl, 3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl,cyclohexenyl, cyclooctenyl or cyclooctadienyl, C₆-C₂₀-aryl which maybear further alkyl groups as substituents, e.g. phenyl, naphthyl,biphenyl, anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5- or2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or3,4,5-trimethylphenyl, or arylalkyl which may bear further alkyl groupsas substituents, e.g. benzyl, o-, m-, p-methylbenzyl, 1- or2-ethylphenyl, where the organic radicals R^(5A) and R^(6A) may also bejoined to form a 5- or 6-membered ring or may be substituted byhalogens, e.g. fluorine, chlorine or bromine, or alkyl or aryl.

In organosilicon substituents SiR^(11A) ₃, possible radicals R^(11A) arethe same radicals as mentioned in more detail above, with it also beingpossible for two R^(11A) to be joined to form a 5- or 6-membered ring,e.g. trimethylsilyl, triethylsilyl, butyldimethylsilyl, tributylsilyl,tri-tert-butylsilyl, triallylsilyl, triphenylsilyl ordimethylphenylsilyl.

The radicals R^(5A) and R^(6A) may be identical or different. Preferredradicals R^(5A) and R^(6A) are hydrogen, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl,n-octyl, benzyl, phenyl, ortho-dialkyl- or ortho-dichloro-substitutedphenyls, trialkyl- or trichloro-substituted phenyls, naphthyl, biphenyland anthranyl.

The bridge Z between the cyclopentadienyl system Cp and theheteroaromatic A is an organic, preferably divalent bridge. Z ispreferably a group CR^(6A)R^(6A). Z is very particularly preferablybound both to the fused heterocycle or fused-on aromatic and to thecyclopentadienyl skeleton. Thus, if the heterocycle or aromatic is fusedon in the 2,3 position of the cyclopentadienyl skeleton, Z is preferablylocated in the 1 or 4 position of the cyclopentadienyl skeleton.

A is an unsubstituted, substituted or fused heteroaromatic, six-memberedring system having 1, 2, 3, 4 or 5 nitrogen atoms in the heteroaromaticpart which is bound to Z, in particular 2-pyridyl or 2-quinolyl.Examples of 6-membered heteroaryl groups, which can contain from one tofive nitrogen atoms, are 2-pyridinyl, 2-pyrimidinyl, 4-pyrimidinyl,2-pyrazinyl, 1,3,5-triazin-2-yl and 1,2,4-triazin-3-yl,1,2,4-triazin-5-yl and 1,2,4-triazin-6-yl. The 6-membered heteroarylgroups may also bear C₁-C₁₀-alkyl groups, C₆-C₁₀-aryl groups, alkylarylgroups having from 1 to 10 carbon atoms in the alkyl part and 6-10carbon atoms in the aryl part, trialkylsilyl groups or halogens such asfluorine, chlorine or bromine as substituents or be fused with one ormore aromatics or heteroaromatics. Examples of benzo-fused 6-memberedheteroaryl groups are 2-quinolyl, 3-cinnolyl, 2-quinazolyl,4-quinazolyl, 2-quinoxalyl, 1-phenanthridyl and 1-phenazyl.

A can bind to the metal M either intermolecularly or intramolecularly. Ais preferably bound intramolecularly to M. The synthesis to bind A tothe cyclopentadienyl ring can be carried out, for example, by a methodanalogous to that of M. Enders et al. in Chem. Ber. (1996), 129,459-463, or P. Jutzi and U. Siemeling in J. Orgmet Chem. (1995), 500,175-185.

Examples of possible carboorganic substituents R^(7A)-R^(10A) in A arethe following: hydrogen, C₁-C₂₀-alkyl which may be linear or branched,e.g. methyl, ethyl, n-propyl, Isopropyl, n-butyl, isobutyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5-to 7-membered cycloalkyl which may in turn bear a C₆-C₁₀-aryl group assubstituent, e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, cyclononyl or cyclododecyl, C₂-C₂₀-alkenylwhich may be linear, cyclic or branched and in which the double bond maybe internal or terminal, e.g. vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl,pentenyl, hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl orcyclooctadienyl, C₆-C₂₀-aryl which may bear further alkyl groups assubstituents, e.g. phenyl, naphthyl, biphenyl, anthranyl, o-, m-,p-methylphenyl, 2,3-, 2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-,2,3,5-,2,3,6-, 2,4,5-, 2,4,6- or 3,4,5-trimethylphenyl, or arylalkyl which maybear further alkyl groups as substituents, e.g. benzyl, o-, m-,p-methylbenzyl, 1- or 2-ethylphenyl, where two vicinal radicals R^(7A)to R^(10A) may also be bound to form a 5- or 6-membered ring or may besubstituted by halogens, e.g. fluorine, chlorine or bromine, or alkyl oraryl. R^(7A)-R^(10A) are preferably each hydrogen, methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, n-octyl, benzyl or phenyl. In organosilicon substituentsSiR^(11A) ₃, possible radicals R^(11A) are the same radicals asmentioned in more detail above, with two R^(11A) also being able to bejoined to form a 5- or 6-membered ring, e.g. trimethylsilyl,triethylsilyl, butyldimethylsilyl, tributylsilyl, tri-tert-butylsilyl,triallylsilyl, triphenylsilyl or dimethylphenylsilyl.

In particular, 0 or 1 E^(1A)-E^(4A) in A is nitrogen and the others arecarbon. A is particularly preferably 2-pyridyl, 6-methyl-2-pyridyl,4-methyl-2-pyridyl, 5-methyl-2-pyridyl, 5-ethyl-2-pyridyl,4,6-dimethyl-2-pyridyl, 3-pyridazyl, 4-pyrimidyl, 6-methyl-4-pyrimidyl,2-pyrazinyl, 6-methyl-2-pyrazinyl, 5-methyl-2-pyrazinyl,3-methyl-2-pyrazinyl, 3-ethyl-2-pyrazinyl, 3,5,6-trimethyl-2-pyrazinyl,2-quinolyl, 4-methyl-2-quinolyl, 6-methyl-2-quinolyl,7-methyl-2-quinolyl, 2-quinoxalyl or 3-methyl-2-quinoxalyl.

The chromium is particularly preferably present in one of the oxidationstates 2, 3 and 4, In particular 3. The chromium complexes can beobtained in a simple manner by reacting the appropriate metal salts,e.g. chromium chlorides, with the ligand anion (e.g. using a methodanalogous to the examples in DE 197 10615).

In the process of the present invention, preference is given tomonocyclopentadienyl complexes A) of the formula (Cp-Z-A)CrX_(k) (Ian),where the variables Cp, Z and A are as defined above and their preferredembodiments are also preferred here and:

-   X are each, independently of one another, fluorine, chlorine,    bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl,    C₆-C₂₀-aryl, alkylaryl having 1-10 carbon atoms in the alkyl part    and 6-20 carbon atoms in the aryl part, NR¹R², OR¹, SR¹, SO₃R¹,    OC(O)R¹, CN, SCN, β-diketonate, CO, BF₄ ⁻, PF₆ ⁻ or a bulky    noncoordinating anion,-   R¹-R² are each, independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part or SiR³ ₃, where the organic radicals R¹-R² may also be    substituted by halogens or nitrogen- and oxygen-containing groups    and two radicals R¹-R² may also be joined to form a five- or    six-membered ring,-   R³ are each, independently of one another, hydrogen, C₁-C₂₀-alkyl,    C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10 carbon    atoms in the alkyl part and 6-20 carbon atoms in the aryl part and    two radicals R³ may also be joined to form a five- or six-membered    ring and-   k is 1, 2 or 3.

The embodiments and preferred embodiments of Cp, Z and A described abovealso apply individually and in combination to these preferredmonocyclopentadienyl complexes A).

The ligands X can result, for example, from the choice of thecorresponding starting chromium compounds which are used for thesynthesis of the monocyclopentadienyl complexes, but can also be variedafterwards. Suitable ligands X are, in particular, the halogensfluorine, chlorine, bromine or iodine, in particular chlorine. Alkylradicals such as methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl orbenzyl are also advantageous ligands X. Further possible ligands X are,purely by way of example and not in any way exhaustively,trifluoroacetate, BF₄ ⁻, PF₆ ⁻ and weakly coordinating ornoncoordinating anions (cf., for example, Strauss in Chem. Rev. 1993,93, 927-942) such as B(C₆F₅)₄ ⁻.

Amides, alkoxides, sulfonates, carboxylates and β-diketonates are alsoparticularly suitable ligands X. Variation of the radicals R¹ and R²enables, for example, physical properties such as solubility to befinely adjusted. Possible carboorganic substituents R¹-R² are, forexample, the following: C₁-C₂₀-alkyl which may be linear or branched,for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl orn-dodecyl, 5- to 7-membered cycloalkyl which may in turn bear aC₆-C₁₀-aryl group as substituent, e.g. cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl orcyclododecyl, C₂-C₂₀-alkenyl which may be linear, cyclic or branched andhave an internal or terminal double bond, e.g. vinyl, 1-allyl, 2-allyl,3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl, cyclohexenyl,cyclooctenyl or cyclooctadienyl, C₆-C₂₀-aryl which may be substituted byfurther alkyl groups and/or N- or O-containing radicals, e.g. phenyl,naphthyl, biphenyl, anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5-or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6-, or3,4,5-trimethylphenyl, 2-methoxyphenyl, 2-N,N-dimethylaminophenyl orarylalkyl which may be substituted by further alkyl groups, e.g. benzyl,o-, m-, p-methylbenzyl, 1- or 2-ethylphenyl, where R¹ may also be joinedto R² to form a 5- or 6-membered ring and the organic radicals R¹-R² mayalso be substituted by halogens, e.g. fluorine, chlorine or bromine. Inorganosilicon substituents SiR³ ₃, R³ may be the same radicals asdescribed in more detail above for R¹-R², with two R³ also being able tobe joined to form a 5- or 6-membered ring. Examples of substituents SiR³₃ are trimethylsilyl, triethylsilyl, butyldimethylsilyl, tributylsilyl,triallylsilyl, triphenylsilyl and dimethylphenylsilyl. Preference isgiven to using C₁-C₁₀-alkyl such as methyl, ethyl, n-propyl, n-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and also vinyl, allyl,benzyl and phenyl as radicals R¹ and R². Some of these substitutedligands X are very particularly preferably used since they areobtainable from cheap and readily available starting materials. In aparticularly preferred embodiment X is dimethylamide, methoxide,ethoxide, isopropoxide, phenoxide, naphthoxide, triflate,p-toluenesulfonate, acetate or acetylacetonate.

The number k of the ligands X depends on the oxidation state of thechromium. The number k can therefore not be specified in general terms.The oxidation state of the transition metals M in catalytically activecomplexes is usually known to a person skilled in the art Chromium isvery probably present in the oxidation state +3. However, it is alsopossible to use complexes whose oxidation state does not correspond tothat of the active catalyst. Such complexes can then be appropriatelyreduced or oxidized by means of suitable activators. Preference is givento using chromium complexes in the oxidation state +3.

Furthermore, we have found catalyst systems for olefin polymerizationcomprising

-   A′) at least one monocyclopentadienyl complex A′) comprising the    structural feature of the formula (Cp-CR^(5B)R^(6B)-A)Cr (IV), where    the variables have the following meanings:    -   Cp-CR^(5B)R^(6B)-A is

-   -   where    -   R^(1B)-R^(4B) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from        1 to 10 carbon atoms in the alkyl radical and 6-20 carbon atoms        in the aryl radical, NR^(5A) ₂, N(SiR^(11B) ₃)₂, OR^(11B),        OSiR^(11B) ₃, SiR^(11B) ₃, BR^(11B) ₂, where the organic        radicals R^(1B)-R^(4B) may also be substituted by halogens and        two vicinal radicals R^(1B)-R^(4B) may also be joined to form a        five- or six-membered ring,    -   R^(5B), R^(6B) are each hydrogen or methyl,    -   A is

-   -   where    -   E^(1B)-E^(4B) are each carbon or nitrogen,    -   R^(7B)-R^(10B) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from        1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in        the aryl part or SiR^(11B) ₃, where the organic radicals        R^(7B)-R^(10B) may also bear halogens or nitrogen or further        C₁-C₂₀-alkyl groups, C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups,        alkylaryl groups having from 1 to 10 carbon atoms in the alkyl        part and 6-20 carbon atoms in the aryl part or SiR^(11B) ₃as        substituents and two vicinal radicals R^(7B)-R^(10B) may also be        joined to form a five- or six-membered ring,    -   R^(11B) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl or alkylaryl having        from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon        atoms in the aryl part and two radicals R^(11B) may also be        joined to form a five- or six-membered ring,    -   p is 0 when E^(1B)-E^(4B) is nitrogen and is 1 when        E^(1B)-E^(4B) is carbon,    -   where at least one radical R^(7B)-R^(10B) is C₁-C₂₀-alkyl,        C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10        carbon atoms in the alkyl part and 6-20 carbon atoms in the aryl        part or SiR^(11B) ₃ and the organic radicals R^(7B)-R^(10B) may        also bear halogens or nitrogen or further C₁-C₂₀-alkyl groups,        C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups, alkylaryl groups        having from 1 to 10 carbon atoms in the alkyl part and 6-20        carbon atoms in the aryl part or SiR^(5C) ₃ as substituents and        two vicinal radicals R^(7B)-R^(10B) may also be joined to form a        five- or six-membered ring or at least one E^(1B)-E^(4B) is        nitrogen,

-   B) optionally an organic or inorganic support,

-   C) optionally one or more activating compounds and

-   D) optionally one or more metal compounds containing a metal of    group 1, 2 or 13 of the Periodic Table.

The monocyclopentadienyl complexes A′) of the present invention comprisethe structural element of the formula (Cp-CR^(5B)R^(6B)-A)Cr (IV), wherethe variables are as defined above. Further ligands can therefore bebound to the metal atom M. The number of further ligands depends, forexample, on the oxidation state of the metal atom. Possible furtherligands do not include further cyclopentadienyl systems. Suitablefurther ligands are monoanionic and dianionic ligands as are described,for example, for x. In addition, Lewis bases such as amines, ethers,ketones, aldehydes, esters, sulfides or phosphines can also be bound tothe metal center M.

The polymerization behavior of the metal complexes can likewise beinfluenced by variation of the substituents R^(1B)-R^(4B). The numberand type of substituents can influence the ability of the olefins to bepolymerized to gain access to the metal atom Cr. This makes it possibleto modify the activity and selectivity of the catalyst in respect ofvarious monomers, in particular bulky monomers. Since the substituentscan also influence the rate of termination reactions of the growingpolymer chain, the molecular weight of the polymers formed can also bealtered in this way. The chemical structure of the substituents R^(1B)to R^(4B) can therefore be varied within a wide range in order toachieve the desired results and to obtain a tailored catalyst system.Possible carboorganic substituents R^(1B)-R^(4B) are, for example, thefollowing: C₁-C₂₀-alkyl which may be linear or branched, e.g. methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5 to7-membered cycloalkyl which may in turn bear a C₆-C₁₀-aryl group assubstituent, e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, cyclononyl or cyclododecyl, C₂-C₂₀-alkenyl,which may be linear, cyclic or branched and in which the double bond canbe internal or terminal, e.g. vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl,pentenyl, hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl orcyclooctadienyl, C₆-C₂₀-aryl which may bear further alkyl groups assubstituents, e.g. phenyl, naphthyl, biphenyl, anthranyl, o-, m-,p-methylphenyl, 2,3-, 2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-,2,3,6-, 2,4,5-, 2,4,6- or 3,4,5-trimethylphenyl, or arylalkyl which maybear further alkyl groups as substituents, e.g. benzyl, o-, m-,p-methylbenzyl, 1- or 2-ethylphenyl, where two R^(1B) to R^(4B) may alsobe joined to form a 5- or 6-membered ring and the organic radicalsR^(1B)-R^(4B) may also be substituted by halogens such as fluorine,chlorine or bromine. Furthermore, R^(1B)-R^(4B) may also be amino oralkoxy, for example dimethylamino, N-pyrrolidinyl, picolinyl, methoxy,ethoxy or isopropoxy. As organosilicon substituents SiR^(11B) ₃, R^(11B)may be the same radicals as described in more detail above for thecarboorganic radicals R^(1B)-R^(4B), with two R^(11B) also being able tobe joined to form a 5- or 6-membered ring, e.g. trimethylsilyl,triethylsilyl, butyldimethylsilyl, tributylsilyl, tri-tert-butylsilyl,triallylsilyl, triphenylsilyl or dimethylphenylsilyl. These SiR^(11B) ₃radicals may also be bound to the cyclopentadienyl skeleton via anoxygen or nitrogen atom, for example trimethylsilyloxy,triethylsilyloxy, butyldimethylsilyloxy, tributylsilyloxy ortri-tert-butylsilyloxy. Preferred radicals R^(1B)-R^(4B) are hydrogen,methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, n-octyl, vinyl, allyl, benzyl, phenyl,ortho-dialkyl or ortho-dichloro-substituted phenyls, trialkyl- ortrichloro-substituted phenyls, naphthyl, biphenyl and anthranyl. Asorganosilicon substituents, particular preference is given totrialkylsilyl groups having from 1 to 10 carbon atoms in the alkylradical, in particular trimethylsilyl groups.

Examples of such cyclopentadienyl systems (without the group—CR^(5B)R^(6B)-A, which is preferably located in the 1 position) are3-methylcyclopentadienyl, 3-ethylcyclopentadienyl,3-isopropyl-cyclopentadienyl, 3-tert-butylcyclopentadienyl,dialkylcyclopentadienyl such as tetrahydroindenyl,2,4-dimethylcyclopentadienyl or 3-methyl-5-tert-butylcyclopentadienyl,trialkylcyclopentadienyl such as 2,3,5-trimethylcyclopentadienyl ortetraalkylcyclopentadienyl such as 2,3,4,5-tetramethyl-cyclopentadienyl.

Preferably at least two of the vicinal radicals R^(1B)-R^(4B) are joinedto form a five- or six-membered ring, and/or two vicinal radicalsR^(1B)-R^(4B) are joined to form a heterocycle which contains at leastone atom from the group consisting of N, P, O and S.

Preference is also given to compounds in which two vicinal radicalsR^(1B)-R^(4B), in particular R^(1B) together with R^(2B) and/or R^(3B)together with R^(4B), form a five- or six-membered ring in particular afused ring system, in particular a C₆ ring system, particularlypreferably an aromatic C₆ ring system, i.e. together with thecyclopentadienyl C₅ ring form, and/or two vicinal radicals R^(1B)-R^(4B)are joined to form a heterocycle which contains at least one atom fromthe group consisting of N, P, O and S. Examples of such systems are anunsubstituted or substituted indenyl, benzindenyl, phenanthrenyl,fluorenyl or tetrahydroindenyl system, e.g. indenyl, 2-methylindenyl,2-ethyl-indenyl, 2-isopropylindenyl, 3-methylindenyl, benzindenyl or2-methylbenzindenyl. In particular, R^(1B) and R^(2B) together with thecyclopentadienyl system form a substituted or unsubstituted indenylsystem.

The fused ring system may bear further C₁-C₂₀-alkyl groups,C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups, alkylaryl groups having from1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the arylpart, NR^(11B) ₂, N(SiR^(11B) ₃)₂, OR^(11B), OSiR^(11B) ₃ or SiR^(11B)₃, e.g. 4-methylindenyl, 4-ethyl-indenyl, 4-isopropylindenyl,5-methylindenyl, 4-phenylindenyl, 5-methyl-4-phenylindenyl,2-methyl-4-phenylindenyl or 4-naphthylindenyl.

As in the case of metallocenes, the monocyclopentadienyl complexes A) ofthe present invention may be chiral. Thus, one of the substituentsR^(1B)-R^(4B) of the cyclopentadienyl skeleton can have one or morechiral centers, or else the cyclopentadienyl system Cp can itself beenantiotopic, so that chirality is induced only when thecyclopentadienyl system is bound to the transition metal M (forformalisms regarding chirality in cyclopentadienyl compounds, cf. R.Halterman, Chem. Rev. 92, (1992), 965-994).

The bridge —CR^(5B)R^(6B)— between the cyclopentadienyl system Cp andthe heteroaromatic A is an organic divalent bridge. —CR^(5B)R^(6B)— canbe —CH₂—, —CHCH₃— or —C(CH₃)²—. —CR^(5B)R^(6B)— is preferably —CH₂— or—CHCH₃—, particularly preferably —CH₂—. —CR^(5B)R^(6B)— is veryparticularly preferably bound both to the fused heterocycle or fused-onaromatic and to the cyclopentadienyl skeleton. Thus, if the heterocycleor aromatic is fused on in the 2,3 position of the cyclopentadienylskeleton, —CR^(5B)R^(6B)— is preferably located in the 1 or 4 positionof the cyclopentadienyl skeleton.

Examples of possible carboorganic substituents R^(7B)-R^(10B) in A arethe following: hydrogen, C₁-C₂₀-alkyl which may be linear or branched,e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-dodecyl, 5-to 7-membered cycloalkyl which may in turn bear a C₆-C₁₀-aryl group assubstituent, e.g. cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, cyclononyl or cyclododecyl, C₂-C₂₀-alkenylwhich may be linear, cyclic or branched and in which the double bond canbe internal or terminal, e.g. vinyl, 1-allyl, 2-allyl, 3-allyl, butenyl,pentenyl, hexenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl orcyclooctadienyl, C₆-C₂₀-aryl which may bear further alkyl groups assubstituents, e.g. phenyl, naphthyl, biphenyl, anthranyl, o-, m-,p-methylphenyl, 2,3-, 2,4-, 2,5- or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-,2,3,6-, 2,4,5-, 2,4,6- or 3,4,5-trimethylphenyl, and arylalkyl which maybear further alkyl groups as substituents, e.g. benzyl, o-, m-,p-methylbenzyl, 1- or 2-ethylphenyl, where two vicinal radicals R^(7B)to R^(10B) may also be joined to form a 5- or 6-membered ring or mayalso be substituted by halogens, e.g. fluorine, chlorine or bromine, oralkyl or aryl. R^(7B)-R^(10B) are each preferably hydrogen, methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,n-hexyl, n-heptyl, n-octyl, benzyl or phenyl. In organosiliconsubstituents SiR^(11B) ₃, possible radicals R^(11B) are the sameradicals mentioned in more detail above for R^(11A), with two R^(11B)also being able to be joined to form a 5- or 6-membered ring, e.g.trimethylsilyl, triethylsilyl, butyldimethylsilyl, tributylsilyl,tri-tert-butylsilyl, triallylsilyl, triphenylsilyl ordimethylphenylsilyl.

A is a substituted or fused heteroaromatic, six-membered ring systemhaving 1, 2, 3, 4 or 5 nitrogen atoms in the heteroaromatic part whichis bound to —CR^(5B)R^(6B)— or an unsubstituted, substituted or fusedheteroaromatic, six-membered ring system having 2, 3, 4 or 5 nitrogenatoms in the heteroaromatic part which is bound to —CR^(5B)R^(6B)—, inparticular 2-quinolyl or substituted 2-pyridyl. Examples of 6-memberedheteroaryl groups, which can contain from two to five nitrogen atoms,are 2-pyrimidinyl, 4-pyrimidinyl, 2-pyrazinyl, 1,3,5-triazin-2-yl and1,2,4-triazin-3-yl, 1,2,4-triazin-5-yl and 1,2,4-triazin-6-yl. The6-membered heteroaryl groups may also bear C₁-C₁₀-alkyl groups,C₆-C₁₀-aryl groups, alkylaryl groups having from 1 to 10 carbon atoms inthe alkyl part and 6-10 carbon atoms in the aryl part, trialkylsilylgroups or halogens such as fluorine, chlorine or bromine as substituentsor be fused with one or more aromatics or heteroaromatics. Examples ofbenzo-fused 6-membered heteroaryl groups are 2-quinolyl, 3-cinnolyl,2-quinazolyl, 4-quinazolyl, 2-quinoxalyl, 1-phenanthridyl and1-phenazyl.

A can bind to the chromium either intermolecularly or intramolecularly.A is preferably bound intramolecularly to Cr. The synthesis to bind A tothe cyclopentadienyl ring can be carried out, for example, by a methodanalogous to that of P. Jutzi and U. Siemeling in J. Orgmet Chem.(1995), 500, 175-185.

In particular, 1 E^(1B)-E^(4B) is nitrogen and the others are carbon. Ais particularly preferably 3-pyridazyl, 4-pyrimidyl,6-methyl-4-pyrimidyl, 2-pyrazinyl, 6-methyl-2-pyrazinyl,5-methyl-2-pyrazinyl, 3-methyl-2-pyrazinyl, 3-ethyl-2-pyrazinyl,3,5,6-trimethyl-2-pyrazinyl, 2-quinolyl, 4-methyl-2-quinolyl,6-methyl-2-quinolyl, 7-methyl-2-quinolyl, 2-quinoxalyl or3-methyl-2-quinoxalyl.

Furthermore, preference is given to monocyclopentadienyl complexes inwhich all E^(1B)-E^(4B) are carbon and at least one, preferably one,radical R^(7B)-R^(10B) is C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl part and6-20 carbon atoms in the aryl part or SiR^(11B) ₃. A is particularlypreferably 6-methyl-2-pyridyl, 4-methyl-2-pyridyl, 5-methyl-2-pyridyl,5-ethyl-2-pyridyl, 4,6-dimethyl-2-pyridyl or 6-benzyl-2-pyridyl.

Chromium is particularly preferably present in one of the oxidationstates 2, 3 and 4, in particular 3. The chromium complexes can beobtained in a simple manner by reacting the appropriate metal salts,e.g. chromium chlorides, with the ligand anion (e.g. using a methodanalogous to the examples in DE 197 10615).

The monocyclopentadienyl complex A′) can be present as a monomeric,dimeric or trimeric compound. It is possible, for example, for one ormore ligands X to bridge two metal centers M. In the process of thepresent invention, preference is given to monocyclopentadienyl complexesA′) of the formula (Cp-CR^(5B)R^(6B)-A)CrX_(k) (VII), where the variableCp-CR^(5B)R^(6B)-A is as defined above and its preferred embodiments arealso preferred here and:

-   X are each, independently of one another, fluorine, chlorine,    bromine, iodine, hydrogen, C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl,    C₆-C₂₀-aryl, alkylaryl having 1-10 carbon atoms in the alkyl part    and 6-20 carbon atoms in the aryl part, NR¹R², OR¹, SR¹, SO₃R¹,    OC(O)R¹, CN, SCN, β-diketonate, CO, BF₄ ⁻, PF₆ ⁻ or a bulky    noncoordinating anion,-   R¹-R² are each, Independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part or SiR³ ₉, where the organic radicals R¹-R² may also be    substituted by halogens or nitrogen- and oxygen-containing groups    and two radicals R¹-R² may also be joined to form a five- or    six-membered ring,-   R³ are each, independently of one another, hydrogen, C₁-C₂₀-alkyl,    C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10 carbon    atoms in the alkyl part and 6-20 carbon atoms in the aryl part and    two radicals R³ may also be joined to form a five-or six-membered    ring and-   k is 1, 2or 3.

The embodiments and preferred embodiments mentioned above forCp-CR^(5B)R^(6B)-A also apply individually and in combination to thesepreferred monocyclopentadienyl complexes A′).

The ligands X can result, for example, from the choice of thecorresponding starting chromium compounds which are used for thesynthesis of the monocyclopentadienyl complexes A′), but can also bevaried afterwards. Suitable ligands X are, in particular, the halogensfluorine, chlorine, bromine or iodine, in particular chlorine. Alkylradicals such as methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl orbenzyl are also advantageous ligands X. Further possible ligands X are,purely by way of example and not in any way exhaustively,trifluoroacetate, BF₄ ⁻, PF₆ ⁻ and weakly coordinating ornoncoordinating anions (cf., for example, Strauss in Chem. Rev. 1993,93, 927-942) such as B(C₆F₅)₄ ⁻.

Amides, alkoxides, sulfonates, carboxylates and β-diketonates are alsoparticularly suitable ligands x. Variation of the radicals R¹ and R²enables, for example, physical properties such as solubility to befinely adjusted. Possible carboorganic substituents R¹-R² are, forexample, the following: C₁-C₂₀-alkyl which may be linear or branched,for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, nil, n-nonyl, n-decyl orn-dodecyl, 5 to 7-membered cycloalkyl which may in turn bear aC₆-C₁₀-aryl group as substituent, e.g. cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl orcyclododecyl, C₂-C₂₀-alkenyl which may be linear, cyclic or branched andhave an internal or terminal double bond, e.g. vinyl, 1-allyl, 2-allyl,3-allyl, butenyl, pentenyl, hexenyl, cyclopentenyl, cyclohexenyl,cyclooctenyl or cyclooctadienyl, C₆-C₂₀-aryl which may be substituted byfurther alkyl groups and/or N- or O-containing radicals, e.g. phenyl,naphthyl, biphenyl, anthranyl, o-, m-, p-methylphenyl, 2,3-, 2,4-, 2,5-or 2,6-dimethylphenyl, 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6- or3,4,5-trimethylphenyl, 2-methoxyphenyl, 2-N,N-dimethylaminophenyl orarylalkyl which may be substituted by further alkyl groups, e.g. benzyl,o-, m-, p-methylbenzyl, 1- or 2-ethylphenyl, where R¹ may also be joinedto R² to form a 5- or 6membered ring and the organic radicals R¹-R² mayalso be substituted by halogens, e.g. fluorine, chlorine or bromine. Inorganosilicon substituents SiR³ ₃, R³ may be the same radicals asdescribed In more detail above for R¹-R², with two R³ also being able tobe joined to form a 5- or 6-membered ring. Examples of substituents SiR³₃ are trimethylsilyl, triethylsilyl, butyldimethylsilyl, tributylsilyl,triallylsilyl, triphenylsilyl and dimethylphenylsilyl. Preference isgiven to using C₁-C₁₀-alkyl such as methyl, ethyl, n-propyl, n-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and also vinyl, allyl,benzyl and phenyl as radicals R¹ and R². Some of these substitutedligands X are very particularly preferably used since they areobtainable from cheap and readily available starting materials. In aparticularly preferred embodiment X is dimethylamide, methoxide,ethoxide, isopropoxide, phenoxide, naphthoxide, triflate,p-toluenesulfonate, acetate or acetylacetonate.

The number k of the ligands X depends on the oxidation state of thechromium. The number k can therefore not be specified in general terms.The oxidation state of the transition metals M in catalytically activecomplexes is usually known to a person skilled in the art Chromium isvery probably present in the oxidation state +3. However, it is alsopossible to use complexes whose oxidation state does not correspond tothat of the active catalyst. Such complexes can then be appropriatelyreduced or oxidized by means of suitable activators. Preference is givento using chromium complexes in the oxidation state +3.

Furthermore, we have found a process for preparing cyclopentadienylsystem anions of the formula (VIIa),

where the variables have the following meanings:

-   -   R^(1B)-R^(4B) are each, independently of one another, hydrogen,        C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from        1 to 10 carbon atoms In the alkyl radical and 6-20 carbon atoms        in the aryl radical, NR^(5A) ₂, N(SiR^(11B) ₃)₂, OR^(11B),        OSiR^(11B) ₃, SiR^(11B) ₃, BR^(11B) ₂, where the organic        radicals R^(1B)-R^(4B) may also be substituted by halogens and        two vicinal radicals R^(1B)-R^(4B) may also be joined to form a        five- or six-membered ring,

-   R^(5B), R^(6B) are each hydrogen or methyl,

-   A is

where

-   E^(1B)-E^(4B) are each carbon or nitrogen,-   R^(7B)-R^(10B) are each, independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part or SiR^(11B) ₃, where the organic radicals R^(7B)-R^(10B)    may also bear halogens or nitrogen or further C₁-C₂₀-alkyl groups,    C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups, alkylaryl groups having    from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in    the aryl part or SiR^(11B) ₃ as substituents and two vicinal    radicals R^(7B)-R^(10B) may also be joined to form a five- or    six-membered ring,-   R^(11B) are each, independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl or alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part and two radicals R^(11B) may also be joined to form a    five- or six-membered ring,-   p is 0 when E^(1B)-E^(4B) is nitrogen and is 1 when E^(1B)-E^(4B) is    carbon,    where at least one radical R^(7B)-R^(10B) is C₁-C₂₀-alkyl,    C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1 to 10 carbon    atoms in the alkyl part and 6-20 carbon atoms in the aryl part or    SiR^(11B) ₃ and the organic radicals R^(7B)-R^(10B) may also bear    halogens or nitrogen or further C₁-C₂₀-alkyl groups, C₂-C₂₀-alkenyl    groups, C₆-C₂₀-aryl groups, alkylaryl groups having from 1 to 10    carbon atoms in the alkyl part and 6-20 carbon atoms in the aryl    part or SiR^(5C) ₃ as substituents and two vicinal radicals    R^(7B)-R^(10B) may also be joined to form a five- or six-membered    ring or at least one E^(1B)-E^(4B) is nitrogen,    which comprises the step a), where, in step a), a fulvene of the    formula (VIIIa)

is reacted with an A⁻ anion of the formula (VIIIa)

where the variables are each as defined above.

The variables and their preferred embodiments have been described above.

Fulvenes have been known for a long time and can be prepared, forexample, as described by Freiesleben, Angew. Chem. 75 (1963), p. 576.

The counteraction of the cyclopentadienyl system anion (VIIa) is thecation of the A⁻ anion. This is generally a metal of group 1 or 2 of thePeriodic Table of the Elements which may bear further ligands.Particular preference is given to lithium, sodium or potassium cationswhich may also bear uncharged ligands such as amines or ethers andmagnesium chloride or magnesium bromide cations which may likewise bearfurther uncharged ligands, in particular lithium, magnesium chloride ormagnesium bromide cations.

The A⁻ anion is usually obtained by a metal-halogen exchange reaction ofA halide with a metal alkyl compound containing a metal of group 1 or 2,in particular lithium, magnesium chloride or magnesium bromide cations.Suitable metal alkyls are, for example, lithium alkyls, magnesiumalkyls, magnesium (alkyl) halides or mixtures thereof. The molar ratioof metal alkyl compound to A halide is usually in the range from 0.4:1to 100:1, preferably in the range from 0.9:1 to 10:1 and particularlypreferably from 0.95:1 to 1.1:1. Examples of such reactions aredescribed, inter alia, by Furukawa et al. in Tet. Lett. 28 (1987), 5845.As solvents, it is possible to use all aprotic solvents, in particularaliphatic and aromatic hydrocarbons such as n-pentane, n-hexane,isohexane, n-heptane, isoheptane, decalin, benzene, toluene,ethylbenzene or xylene or ethers such as diethyl ether, dibutyl ether,tetrahydrofuran, dimethoxyethane or diethylene glycol dimethyl ether andmixtures thereof. The halogen-metal exchange can be carried out at from-100 to +160° C., in particular from −80 to 100° C. At temperaturesabove 40° C., preference is given to using aromatic or aliphaticsolvents which contain no ethers or only small proportions of ethers.Particularly preferred A⁻ systems are 2-pyridinyl, 3-pyridazinyl,2-pyrimidinyl, 4-pyrimidinyl, 2-pyrazinyl, 2-quinolyl, 3-cinnolyl,2-quinazolyl or 4-quinazolyl.

The A⁻ anion formed by metal-halogen exchange can be isolated but ispreferably reacted with the fulvene (VIIIa) without further isolation.As solvents for the further reaction, it is possible to use all aproticsolvents, in particular aliphatic and aromatic hydrocarbons such asn-pentane, n-hexane, isohexane, n-heptane, isoheptane, decalin, benzene,toluene, ethylbenzene or xylene or ethers such as diethyl ether, dibutylether, tetrahydrofuran, dimethoxyethane or diethylene glycol dimethylether and mixtures thereof. The deprotonation can be carried out at from−100 to +160° C., preferably from −80 to 100° C. and particularlypreferably from 0 to 60° C. At temperatures above 40° C. preference isgiven to using aromatic or aliphatic solvents which contain no ethers oronly small proportions of ethers.

The cyclopentadienyl system anion (VIIIa) obtained in this way can thenbe reacted further with the appropriate transition metal compound, e.g.chromium bichloride tris(tetrahydrofuran), to give the correspondingmonocyclopentadienyl complex (A).

Furthermore, we have found a process for preparing cyclopentadienesystems of the formula (VIIb),

where the variables have the following meanings:

-   E^(1C)-E^(5C) are each carbon, where four adjacent E^(1C)-E^(5C)    form a conjugated diene system and the remaining E^(1C)-E^(5C)    additionally bears a hydrogen atom,-   R^(1B)-R^(4B) are each, independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, aryl, alkylaryl having    from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in    the aryl part, NR^(5A) ₂, N(SiR^(11B) ₃)₂, OR^(11B), OSiR^(11B) ₃,    SiR^(11B) ₃, BR^(11B) ₂, where the organic radicals R^(1B)-R^(4B)    may also be substituted by halogens and two vicinal radicals    R^(1B)-R^(4B) may also be joined to form a five- or six-membered    ring,-   R^(5B),R^(6B) are each hydrogen or methyl,-   A is

where

-   E^(1B)-E^(4B) are each carbon or nitrogen,-   R^(7B)-R^(10B) are each, independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl, alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms In the    aryl part or SiR^(11B) ₃, where the organic radicals R^(7B)-R^(10B)    may also bear halogens or nitrogen or further C₁-C₂₀-alkyl groups,    C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl groups, alkylaryl groups having    from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in    the aryl part or SiR^(11B) ₃ as substituents and two vicinal    radicals R^(7B)-R^(10B) may also be joined to form a five- or    six-membered ring,-   R^(11B) are each, independently of one another, hydrogen,    C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl or alkylaryl having from 1    to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the    aryl part and two radicals R^(11B) may also be joined to form a    five- or six-membered ring,-   p is 0 when E^(1B)-E^(4B) is nitrogen and is 1 when E^(1B)-E^(4B) is    carbon,    where at least one R^(7B)-R^(10B) is C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl,    C₆-C₂₀-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl    part and 6-20 carbon atoms in the aryl part or SiR^(11B) ₃ and the    organic radicals R^(7B)-R^(10B) may also bear halogens or nitrogen    or further C₁-C₂₀-alkyl groups, C₂-C₂₀-alkenyl groups, C₆-C₂₀-aryl    groups, alkylaryl groups having from 1 to 10 carbon atoms in the    alkyl part and 6-20 carbon atoms in the aryl part or SiR^(5C) ₃ as    substituents and two vicinal radicals R^(7B)-R^(10B) may also be    joined to form a five- or six-membered ring or at least one    E^(1B)-E^(4B) is nitrogen, which comprises the following step:-   a′) reaction of an A-CR^(5B)R^(6B-) anion with a cyclopentenone    system of the formula (IX)

where the variables are as defined above.

The variables and their preferred embodiments have been described aboveand those definitions also apply in this process.

The cation of the A-CR^(5B)R^(6B-) anion is generally a metal of group 1or 2 of the Periodic Table of the Elements which may bear furtherligands. Particular preference is given to lithium, sodium or potassiumcations which may also bear uncharged ligands such as amines or ethersand magnesium chloride or magnesium bromide cations which may likewisebear further uncharged ligands.

The A-CR^(5B)R^(6B-) anion is usually obtained by deprotonation ofA-CR^(5B)R^(6B)H. This can be carried out using strong bases such aslithium alkyls, sodium hydride, sodium amides, sodium alkoxides, sodiumalkyls, potassium hydride, potassium amides, potassium alkoxides,potassium alkyls, magnesium alkyls, magnesium (alkyl) halides ormixtures thereof. The molar ratio of base to A-CR^(5B)R^(6B)H is usuallyin the range from 0.4:1 to 100:1, preferably in the range from 0.9:1 to10:1 and particularly preferably from 0.95:1 to 1.1:1. Examples of suchdeprotonations are described in L. Brandsma, Preparative polarorganometallic chemistry 2, pp. 133-142.

As solvents In the deprotonation step, it is possible to use all aproticsolvents, In particular aliphatic and aromatic hydrocarbons such asn-pentane, n-hexane, isohexane, n-heptane, isoheptane, decalin, benzene,toluene, ethylbenzene or xylene or ethers such as diethyl ether, dibutylether, tetrahydrofuran, dimethoxyethane or diethylene glycol dimethylether and mixtures thereof. The deprotonation can be carried out at from−100 to +160° C., in particular from −80 to 100° C. At temperaturesabove 40° C., preference is given to using aromatic or aliphaticsolvents which contain no ethers or only small proportions of ethers assolvent.

A-CR^(5B)R^(6B)H is particularly preferably a group of the formula(VIIIb)

where the variables are as defined above.

The CR^(6B)R^(6B)H group is preferably located in the ortho positionrelative to a nitrogen atom of A. A-CR^(5B)R^(6B)H is preferably2,6-lutidine, 2,4-lutidine, 2,5-lutidine, 2,3-cycloheptenopyridine,5-ethyl-2-methylpyridine, 2,4,6-collidine, 3-methylpyridazine,4-methylpyrimidine, 4,6-dimethylpyrimidine, 2-methylpyrazine,2-ethylpyrazine, 2,6-dimethylpyrazine, 2,5-dimethylpyrazine,2,3-dimethylpyrazine, 2,3-diethylpyrazine, tetrahydroquinoxaline,tetramethylpyrazine, quinaldine, 2,4-dimethylquinoline,2,6-dimethylquinoline, 2,7-dimethylquinoline, 2-methylquinoxaline,2,3-dimethylquinoxaline or neocuproin.

The A-CR^(5B)R^(6B) anion formed after deprotonation can be isolated butis preferably reacted with the cyclopentenone (IX) without furtherisolation. As solvents for the further reaction, it is possible to useall aprotic solvents, in particular aliphatic and aromatic hydrocarbonssuch as n-pentane, n-hexane, isohexane, n-heptane, isoheptane, decalin,benzene, toluene, ethylbenzene or xylene or ethers such as diethylether, dibutyl ether, tetrahydrofuran, dimethoxyethane or diethyleneglycol dimethyl ether and mixtures thereof. The reaction with thecyclopentenone (IX) can be carried out at from −100 to +160° C.,preferably from −80 to 100° C. and particularly preferably from 0 to 60°C. At temperatures above 40° C., preference is given to using aromaticor aliphatic solvents which contain no ethers or only small proportionsof ethers as solvent.

The cyclopentenolate formed by reaction of the A-CR^(5B)R^(6B-) anionwith the cyclopentenone (IX) is usually protonated before dehydration.This can be carried out, for example, by means of small amounts of acid,for example HCl, or by means of an aqueous work-up. The intermediateobtained in this way, viz. a cyclopentenol, is subsequently dehydrated.This is often carried out with addition of catalytic amounts of acid,e.g. HCl or p-toluenesulfonic acid, or Iodine. Dehydration can becarried out at from −10 to +160° C., preferably from 0 to 100° C. andparticularly preferably from 20 to 80° C. As solvents, it is possible touse aprotic solvents, in particular aliphatic and aromatic hydrocarbonssuch as n-pentane, n-hexane, isohexane, n-heptane, isoheptane, decalin,benzene, toluene, ethylbenzene or xylene or ethers such as diethylether, dibutyl ether, tetrahydrofuran, dimethoxyethane or diethyleneglycol dimethyl ether and mixtures thereof. Particularly useful solventsare toluene or heptane. Water separators are often also utilized for thedehydration.

This method of preparing the cyclopentadiene systems (VIIIb) isparticularly advantageous since it is carried out using simple startingmaterials and gives good yields. The by-products formed (dehydration inthe exo position) can be separated off in a simple manner by the furtherreactions to form the monocyclopentadienyl complex. The cyclopentadienesystem (VIIb) obtained in this way can be deprotonated by customarymethods, for example using potassium hydride or n-butyllithium, andreacted further with the appropriate transition metal compound, e.g.chromium trichloride tris(tetrahydrofuran), to give the correspondingmonocyclopentadienyl complex (A′). The by-products undergo none of thesereactions. Furthermore, the cyclopentadiene system (VIIb) can also bereacted directly with, for example, chromium amides to give themonocyclopentadienyl complex (A′) in a manner analogous to the processin EP-A-742 046. The monocyclopentadienyl complexes of the presentinvention can be used alone or together with further components ascatalyst systems for olefin polymerization.

For the monocyclopentadienyl complexes A) or A′) to be able to be usedin polymerization processes in the gas phase or in suspension, it isoften advantageous to use the metallocenes in the form of a solid, i.e.for them to be applied to a solid support B). Furthermore, the supportedmonocyclopentadienyl complexes have a high productivity. Themonocyclopentadienyl complexes A) or A′) can therefore also, if desired,be immobilized on an organic or inorganic support B) and used insupported form in the polymerization. This enables, for example,deposits in the reactor to be avoided and the polymer morphology to becontrolled. As support materials, preference is given to using silicagel, magnesium chloride, aluminum oxide, mesoporous materials,aluminosilicates, hydrotalcites and organic polymers such aspolyethylene, polypropylene, polystyrene, polytetrafluoroethylene orpolar functionalized polymers, e.g. copolymers of ethene and acrylicesters, acrolein or vinyl acetate.

Particular preference is given to a catalyst system comprising amonocyclopentadienyl complex A) or A′) and at least one activatingcompound C) and also a support component B).

To obtain such a supported catalyst system, the unsupported catalystsystem A) or A′) can be reacted with a support component B). The orderin which the support component B), the monocyclopentadienyl complex A)or A′) and the activating compound C) are combined is in principleimmaterial. The monocyclopentadienyl complex A) or A′) and theactivating compound C) can be immobilized independently of one another,e.g. in succession or simultaneously. Thus, the support component B) canfirstly be brought into contact with the activating compound orcompounds C) or the support component B) can firstly be brought intocontact with the monocyclopentadienyl complex A) or A′). Preactivationof the monocyclopentadienyl complex A) or A′) using one or moreactivating compounds C) before mixing with the support B) is alsopossible. In one possible embodiment, the metal complex (A) can also beprepared in the presence of the support material. A further method ofimmobilization is prepolymerization of the catalyst system with orwithout prior application to a support

Immobilization is generally carried out in an inert solvent which can beremoved by filtration or evaporation after immobilization has beencarried out. After the individual process steps, the solid can be washedwith suitable inert solvents such as aliphatic or aromatic hydrocarbonsand dried. However, the use of the still moist, supported catalyst isalso possible.

In a preferred method of preparing the supported catalyst system, atleast one of the monocyclopentadienyl complexes A) or A′) is broughtinto contact with at least one activating compound C) in a suitablesolvent, preferably giving a soluble reaction product, an adduct or amixture. The preparation obtained in this way is then mixed with thedehydrated or passivated support material, the solvent is removed andthe resulting supported monocyclopentadienyl complex catalyst system isdried to ensure that all or most of the solvent has been removed fromthe pores of the support material. The supported catalyst is obtained asa free-flowing powder. Examples of the industrial implementation of theabove process are described in WO 96/00243, WO 98140419 or WO 00/05277.A further preferred embodiment comprises firstly applying the activatingcompound C) to the support component B) and subsequently bringing thissupported compound into contact with the monocyclopentadienyl complex A)or A′).

As support component B), preference is given to using finely dividedsupports which can be any organic or inorganic solids. In particular,the support component B) can be a porous support such as talc, a sheetsilicate such as montmorillonite, mica, an inorganic oxide or a finelydivided polymer powder (e.g. a polyolefin or a polymer having polarfunctional groups).

The support materials used preferably have a specific surface area inthe range from 10 to 1 000 m²/g, a pore volume in the range from 0.1 to5 ml/g and a mean particle size of from 1 to 500 μm. Preference is givento supports having a specific surface area in the range from 50 to 700m²/g, a pore volume in the range from 0.4 to 3.5 ml/g and a meanparticle size in the range from 5 to 350 μm. Particular preference Isgiven to supports having a specific surface area In the range from 200to 550 m²/g, a pore volume in the range from 0.5 to 3.0 ml/g and a meanparticle size of from 10 to 150 μm.

The inorganic support can be subjected to a thermal treatment, e.g. toremove adsorbed water. Such a drying treatment is generally carried outat from 80 to 300° C., preferably from 100 to 200° C. Drying at from 100to 200° C. is preferably carried out under reduced pressure and/or undera blanket of inert gas (e.g. nitrogen), or the inorganic support can becalcined at from 200 to 1 000° C. to produce the desired structure ofthe solid and/or the desired OH concentration on the surface. Thesupport can also be treated chemically using customary desiccants suchas metal alkyls, preferably aluminum alkyls, chlorosilanes or SiCl₄, orelse methylaluminoxane. Appropriate treatment methods are described, forexample, in WO 00/31090.

The inorganic support material can also be chemically modified. Forexample, the treatment of silica gel with NH₄SiF₆ or other fluorinatingagents leads to fluorination of the silica gel surface, or treatment ofsilica gels with silanes containing nitrogen-, fluorine- orsulfur-containing groups leads to correspondingly modified silica gelsurfaces.

Organic support materials such as finely divided polyolefin powders(e.g. polyethylene, polypropylene or polystyrene) can also be used andare preferably likewise freed of adhering moisture, solvent residues orother impurities by appropriate purification and drying operationsbefore use. It is also possible to use functionalized polymer supports,e.g. ones based on polystyrene, polyethylene or polypropylene, via whosefunctional groups, for example ammonium or hydroxy groups, at least oneof the catalyst components can be fixed.

Inorganic oxides suitable as support component B) may be found among theoxides of elements of groups 2, 3, 4, 5, 13, 14, 15 and 16 of thePeriodic Table of the Elements. Examples of oxides preferred as supportsinclude silicon dioxide, aluminum oxide and mixed oxides of the elementscalcium, aluminum, silicon, magnesium or titanium and also correspondingoxide mixtures. Other inorganic oxides which can be used alone or incombination with the abovementioned preferred oxidic supports are, forexample, MgO, CaO, AlPO₄, ZrO₂, TiO₂, B₂O₃ or mixtures thereof.

As solid support materials B) for catalysts for olefin polymeration,preference is given to using silica gels since particles whose size andstructure make them suitable as supports for olefin polymerization canbe produced from this material. Spray-dried silica gels comprisingspherical agglomerates of smaller granular particles, i.e. primaryparticles, have been found to be particularly useful. The silica gelscan be dried and/or calcined before use.

Further preferred supports B) are hydrotalcites and calcinedhydrotalcites. In mineralogy, hydrotalcite is a natural mineral havingthe ideal formulaMg₆Al₂(OH)₁₆CO₃.4H₂Owhose structure is derived from that of brucite Mg(OH)₂. Brucitecrystallizes in a sheet structure with the metal ions in octahedralholes between two layers of close-packed hydroxyl ions, with only everysecond layer of the octahedral holes being occupied. In hydrotalcite,some magnesium ions are replaced by aluminum ions, as a result of whichthe packet of layers gains a positive charge. This is compensated by theanions which are located together with water of crystallization in thelayers in between.

Such sheet structures are found not only in magnesium-aluminumhydroxides, but also generally in mixed metal hydroxides of the formulaM(II)_(2x) ²⁺M(III)₂ ³⁺(OH)_(4x+4).A_(2/n) ^(n-) .zH₂Owhich have a sheet structure and in which M(II) is a divalent metal suchas Mg, Zn, Cu, Ni, Co, Mn, Ca and/or Fe and M(III) is a trivalent metalsuch as Al, Fe, Co, Mn, La, Ce and/or Cr, x is from 0.5 to 10 in stepsof 0.5, A is an interstitial anion and n is the charge on theinterstitial anion which can be from 1 to 8, usually from 1 to 4, and zis an integer from 1 to 6, in particular from 2 to 4. Possibleinterstitial anions are organic anions such as alkoxide anions, alkylether sulfates, aryl ether sulfates or glycol ether sulfates, inorganicanions such as, in particular, carbonate, hydrogencarbonate, nitrate,chloride, sulfate or B(OH)₄ ⁻ or polyoxo metal anions such as Mo₇O₂₄ ⁶⁻or V₁₀O₂₈ ⁶⁻. However, a mixture of a plurality of such anions can alsobe present.

Accordingly, all such mixed metal hydroxides having a sheet structureshould be regarded as hydrotalcites for the purposes of the presentinvention.

Calcined hydrotalcites can be prepared from hydrotalcites bycalcination, i.e. heating, by means of which the desired hydroxyl groupcontent can be set. In addition, the crystal structure also changes. Thepreparation of the calcined hydrotalcites used according to the presentinvention is usually carried out at temperatures above 180° C.Preference is given to calcination for from 3 to 24 hours at from 250° Cto 1 000° C., in particular from 400° C. to 700° C. It is possible forair or inert gas to be passed over the solid or a vacuum to be appliedduring this step.

On heating, the natural or synthetic hydrotalcites firstly give offwater, i.e. drying occurs. On further heating, the actual calcination,the metal hydroxides are converted Into the metal oxides by eliminationof hydroxyl groups and interstitial anions; OH groups or interstitialanions such as carbonate can also still be present in the calcinedhydrotalcites. A measure of this is the loss on ignition. This is theweight loss experienced by a sample which is heated in two steps firstlyfor 30 minutes at 200° C. in a drying oven and then for 1 hour at 950°C. in a muffle furnace.

The calcined hydrotalcites used as component B) are thus mixed oxides ofthe divalent and trivalent metals M(II) and M(III), with the molar ratioof M(II) to M(III) generally being in the range from 0.5 to 10,preferably from 0.75 to 8 and in particular from 1 to 4. Furthermore,normal amounts of impurities, for example Si, Fe, Na, Ca or Ti and alsochlorides and sulfates, can also be present.

Preferred calcined hydrotalcites B) are mixed oxides in which M(II) ismagnesium and M(III) is aluminum. Such aluminum-magnesium mixed oxidesare obtainable from Condea Chemie GmbH (now Sasol Chemie), Hamburg,under the trade name Puralox Mg.

Preference is also given to calcined hydrotalcites in which thestructural transformation is complete or virtually complete.Calcination, i.e. transformation of the structure, can be confirmed, forexample, by means of X-ray diffraction patterns.

The hydrotalcites, calcined hydrotalcites or silica gels employed aregenerally used as finely divided powders having a mean particle diameterd₅₀ of from 5 to 200 μm, preferably from 10 to 150 μm, particularlypreferably from 15 to 100 μm and in particular from 20 to 70 μm, andusually have pore volumes of from 0.1 to 10 cm³/g, preferably from 0.2to 5 cm³/g, and specific surface areas of from 30 to 1 000 m²/g,preferably from 50 to 800 m²/g and in particular from 100 to 600 m²/g.The monocyclopentadienyl complexes of the present invention arepreferably applied in such an amount that the concentration ofmonocyclopentadienyl complexes in the finished catalyst system is from 5to 200 μmol, preferably from 20 to 100 μmol and particularly preferablyfrom 25 to 70 μmol per g of support B).

Some of the monocyclopentadienyl complexes A) or A′) have littlepolymerization activity on their own and are then brought into contactwith an activator, viz. the component C), to be able to display goodpolymerization activity. For this reason, the catalyst system optionallyfurther comprises, as component C), one or more activating compounds,preferably at least one activating compound C).

Suitable compounds C) which are able to react with themonocyclopentadienyl complex A) or A′) to convert it into acatalytically active, or more active, compound are, for example,compounds such as an aluminoxane, a strong uncharged Lewis acid, anionic compound having a Lewis-acid cation or an ionic compoundcontaining a Brönsted acid as cation.

The amount of activating compounds to be used depends on the type ofactivator. In general, the molar ratio of metal complex A) or A′) toactivating compound C) can be from 1:0.1 to 1:10 000, preferably from1:1 to 1:2 000.

As aluminoxanes, it is possible to use, for example, the compoundsdescribed in WO 00/31090. Particularly useful aluminoxanes areopen-chain or cyclic aluminoxane compounds of the formula (X) or (XI)

where

-   R^(1D)-R^(4D) are each, independently of one another, a C₁-C₆-alkyl    group, preferably a methyl, ethyl, butyl or isobutyl group, and 1 is    an integer from 1 to 40, preferably from 4 to 25.

A particularly useful aluminoxane compound is methylaluminoxane.

These oligomeric aluminoxane compounds are usually prepared bycontrolled reaction of a solution of trialkylaluminum, in particulartrimethylaluminum, with water. In general, the oligomeric aluminoxanecompounds obtained in this way are in the form of mixtures of bothlinear and cyclic chain molecules of various lengths, so that 1 is to beregarded as a mean. The aluminoxane compounds can also be present inadmixture with other metal alkyls, usually aluminum alkyls. Aluminoxanepreparations suitable as component C) are commercially available.

Furthermore, modified aluminoxanes in which some of the hydrocarbonradicals have been replaced by hydrogen atoms or alkoxy, aryloxy, siloxyor amide radicals can also be used as component C) in place of thealuminoxane compounds of the formula (X) or (XI).

It has been found to be advantageous to use the monocyclopentadienylcomplexes A) or A′) and the aluminoxane compounds in such amounts thatthe atomic ratio of aluminum from the aluminoxane compounds includingany aluminum alkyl still present to the transition metal from themonocyclopentadienyl complex A) or A′) is in the range from 1:1 to 2000:1, preferably from 10:1 to 500:1 and in particular in the range from20:1 to 400:1.

A further class of suitable activating components C) arehydroxyaluminoxanes. These can be prepared, for example, by addition offrom 0.5 to 1.2 equivalents of water, preferably from 0.8 to 1.2equivalents of water, per equivalent of aluminum to an alkylaluminumcompound, in particular triisobutylaluminum, at low temperatures,usually below 0° C. Such compounds and their use in olefinpolymerization are described, for example, in WO 00/24787. The atomicratio of aluminum from the hydroxyaluminoxane compound to the transitionmetal from the monocyclopentadienyl complex A) or A′) is usually in therange from 1:1 to 100:1, preferably from 10:1 to 50:1 and In particularin the range from 20:1 to 40:1. Preference is given to using amonocyclopentadienyl metal dialkyl compound A) or A′).

As strong, uncharged Lewis acids, preference is given to compounds ofthe formula (XII)M^(2D)X^(1D)X^(2D)X^(3D)  (XII)where

-   M^(2D) is an element of group 13 of the Periodic Table of the    Elements, in particular B, Al or Ga, preferably B,-   X^(1D), X^(2D) and X^(3D) are each hydrogen, C₁-C₁₀-alkyl,    C₆-C₁₅-aryl, alkylaryl, arylalkyl, haloalkyl or haloaryl each having    from 1 to 10 carbon atoms in the alkyl radical and from 6 to 20    carbon atoms in the aryl radical or fluorine, chlorine, bromine or    iodine, in particular haloaryls, preferably pentafluorophenyl.

Further examples of strong, uncharged Lewis acids are given in WO00/31090.

Compounds of this type which are particularly useful as component C) areboranes and boroxins such as trialkylborane, triarylborane ortrimethylboroxin. Particular preference is given to using boranes whichbear at least two perfluorinated aryl radicals. Particular preference isgiven to compounds of the formula (XII) in which X^(1D), X^(2D) andX^(3D) are identical, preferably tris(pentafluorophenyl)borane.

Suitable compounds C) are preferably prepared by reaction of aluminum orboron compounds of the formula (XII) with water, alcohols, phenolderivatives, thiophenol derivatives or aniline derivatives, withhalogenated and especially perfluorinated alcohols and phenols being ofparticular importance. Examples of particularly useful compounds arepentafluorophenol, 1,1-bis(pentafluorophenyl)methanol and4-hydroxy-2,2′,3,3′,4,4′,5,5′,6,6′-nonafluorobiphenyl. Examples ofcombinations of compounds of the formula (XII) with Brönsted acids are,in particular, trimethylaluminum/pentafluorophenol,trimethylaluminum/1-bis(pentafluorophenyl)methanol,trimethylaluminum/4-hydroxy-2,2′,3,3′,4,4′,5,5′,6,6′-nonafluorobiphenyl,triethylaluminum/pentafluorophenol andtriisobutylaluminum/pentafluorophenol andtriethylaluminum/4,4′-dihydroxy-2,2′,3,3′,5,5′,6,6′-octafluorobiphenylhydrate.

In further suitable aluminum and boron compounds of the formula (XII),R^(1D) is an OH group. Examples of compounds of this type are boronicacids and borinic acids, in particular borinic acids havingperfluorinated aryl radicals, for example (C₆F₆)₂BOH.

Strong uncharged Lewis acids suitable as activating compounds C) alsoinclude the reaction products of a boronic acid with two equivalents ofan aluminum trialkyl or the reaction products of an aluminum trialkylwith two equivalents of an acidic fluorinated, in particularperfluorinated, hydrocarbon compound such as pentafluorophenol orbis(pentafluorophenyl)borinic acid.

The suitable ionic compounds having Lewis acid cations include salt-likecompounds of the cation of the formula (XIII)[((M^(3D))^(a+)Q) ₁Q₂ . . . Q_(z)]^(d+)  (XIII)where

-   M^(3D) is an element of groups 1 to 16 of the Periodic Table of the    Elements,-   Q₁ to Q_(z) are singly negatively charged groups such as    C₁-C₂₈-alkyl, C₆-C₁₅-aryl, alkylaryl, arylalkyl, haloalkyl, haloaryl    each having from 6 to 20 carbon atoms in the aryl radical and from 1    to 28 carbon atoms in the alkyl radical, C₃-C₁₀-cycloalkyl which may    bear C₁-C₁₀-alkyl groups as substituents, halogen, C₁-C₂₈-alkoxy,    C₆-C₁₅-aryloxy, silyl or mercaptyl groups,-   a is an integer from 1 to 6 and-   z is an integer from 0 to 5,-   d corresponds to the difference a-z, but d is greater than or equal    to 1.

Particularly useful cations are carbonium cations, oxonium cations andsulfonium cations and also cationic transition metal complexes.Particular mention may be made of the triphenylmethyl cation, the silvercation and the 1,1′-dimethylferrocenyl cation. They preferably havenoncoordinating counterions, in particular boron compounds as are alsomentioned in WO 91/09882, preferably tetrakis(pentafluorophenyl)borate.

Salts having noncoordinating anions can also be prepared by combining aboron or aluminum compound, e.g. an aluminum alkyl, with a secondcompound which can react to link two or more boron or aluminum atoms,e.g. water, and a third compound which forms an ionizing ionic compoundwith the boron or aluminum compound, e.g. triphenylchloromethane, oroptionally a base, preferably an organic nitrogen-containing base, forexample an amine, an aniline derivative or a nitrogen heterocycle. Inaddition, a fourth compound which likewise reacts with the boron oraluminum compound, e.g. pentafluorophenol, can be added.

Ionic compounds containing Brönsted acids as cations preferably likewisehave noncoordinating counterions. As Brönsted acid, particularpreference is given to protonated aniline or aniline derivatives.Preferred cations are N,N-dimethylanilinium,N,N-dimethylcyclohexylammonium and N,N-dimethylbenzylammonium and alsoderivatives of the latter two.

Compounds containing anionic boron heterocycles as are described in WO97/36937 are also suitable as component C), in particulardimethylanilinium boratabenzene or trityl boratabenzene.

Preferred ionic compounds C) contain borates which bear at least twoperfluorinated aryl radicals. Particular preference is given toN,N-dimethylanilinium tetrakis(pentafluorophenyl)borate and inparticular N,N-dimethylcyclohexylammoniumtetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammoniumtetrakis(pentafluorophenyl)borate or trityltetrakispentafluorophenylborate.

It is also possible for two or more borate anions to be joined to oneanother, as in the dianion [(C₆F₅)₂B—C₆F₄—B(C₆F₅)₂]²⁻, or the borateanion can be bound via a bridge to a suitable functional group on thesupport surface.

Further suitable activating compounds C) are listed in WO 00/31090.

The amount of strong, uncharged Lewis acids, ionic compounds havingLewis-acid cations or ionic compounds containing Brönsted acids ascations is preferably from 0.1 to 20 equivalents, more preferably from 1to 10 equivalents and particularly preferably from 1 to 2 equivalents,based on the monocyclopentadienyl complex A) or A′).

Suitable activating compounds C) also include boron-aluminum compoundssuch as di[bis(pentafluorophenyl)boroxy]methylalane. Examples of suchboron-aluminum compounds are those disclosed in WO 99/06414.

It is also possible to use mixtures of all the abovementioned activatingcompounds C). Preferred mixtures comprise aluminoxanes, in particularmethylaluminoxane, and an ionic compound, in particular one containingthe tetrakis(pentafluorophenyl)borate anion, and/or a strong unchargedLewis acid, in particular tris(pentafluorophenyl)borane or a boroxin.

Both the monocyclopentadienyl complexes A) or A′) and the activatingcompounds C) are preferably used in a solvent, preferably an aromatichydrocarbon having from 6 to 20 carbon atoms, in particular xylenes,toluene, pentane, hexane, heptane or a mixture thereof.

A further possibility is to use an activating compound C) which cansimultaneously be employed as support B). Such systems are obtained, forexample, from an inorganic oxide by treatment with zirconium alkoxideand subsequent chlorination, for example by means of carbontetrachloride. The preparation of such systems is described, forexample, in WO 01/41920.

The catalyst system can further comprise, as additional component D), ametal compound of the formula (XX),M^(G)(R^(1G))_(r) _(G) (R^(2G))_(s) _(G) (R^(3G))_(t) _(G)   (XX)where

-   M^(G) is Li, Na, K, Be, Mg, Ca, Sr, Ba, boron, aluminum, gallium,    indium, thallium, zinc, in particular Li, Na, K, Mg, boron, aluminum    or Zn,-   R^(1G) is hydrogen, C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl or    arylalkyl each having from 1 to 10 carbon atoms in the alkyl part    and from 6 to 20 carbon atoms in the aryl part,-   R^(2G) and R^(3G) are each hydrogen, halogen, C₁-C₁₀-alkyl,    C₆-C₁₅-aryl, alkylaryl, arylalkyl or alkoxy each having from 1 to 20    carbon atoms in the alkyl radical and from 6 to 20 carbon atoms in    the aryl radical, or alkoxy containing C₁-C₁₀-alkyl or C₆-C₁₅-aryl,-   r^(G) is an integer from 1 to 3 and-   s^(G) and t^(G) are integers from 0 to 2, with the sum    r^(G)+s^(G)+t^(G) corresponding to the valence of M^(G),    where the component D) is usually not identical to the component C).    It is also possible to use mixtures of various metal compounds of    the formula (XX).

Among the metal compounds of the formula (XX), preference is given tothose in which

-   M^(G) is lithium, magnesium, boron or aluminum and-   R^(1G) is C₁-C₂₀-alkyl.

Particularly preferred metal compounds of the formula (XX) aremethyllithium, ethyllithium, n-butyllithium, methylmagnesium chloride,methylmagnesium bromide, ethylmagnesium chloride, ethylmagnesiumbromide, butylmagnesium chloride, dimethylmagnesium, diethylmagnesium,dibutylmagnesium, n-butyl-n-octylmagnesium, n-butyl-n-heptylmagnesium,in particular n-butyl-n-octylmagnesium, tri-n-hexylaluminum,triisobutylaluminum, tri-butylaluminum, triethylaluminum,dimethylaluminum chloride, dimethylaluminum fluoride, methylaluminumdichloride, methylaluminum sesquichloride, diethylaluminum chloride andtrimethylaluminum and mixtures thereof. The partial hydrolysis productsof aluminum alkyls with alcohols can also be used.

When a metal compound D) is used, it is preferably present in thecatalyst system in such an amount that the molar ratio of M^(G) fromformula (XX) to transition metal from monocyclopentadienyl compound A)or A′) is from 2 000:1 to 0.1:1, preferably from 800:1 to 0.2:1 andparticularly preferably from 100:1 to 1:1.

In general, the metal compound D) of the formula (XX) is used asconstituent of a catalyst system for the polymerization orcopolymerization of olefins. Here, the metal compound D) can be used,for example, for preparing a catalyst solid comprising the support B)and/or can be added during or shortly before the polymerization. Themetal compounds D) used can be identical or different. It is alsopossible, particularly when the catalyst solid does not contain anyactivating component C), for the catalyst system to further comprise, inaddition to the catalyst solid, one or more activating compounds C)which are identical to or different from any compounds D) present in thecatalyst solid.

To prepare the catalyst systems of the present invention, preference isgiven to immobilizing at least one of the components A) or A′) and/or C)on the support B) by physisorption or by means of chemical reaction,i.e. covalent binding of the components, with reactive groups of thesupport surface. The order in which the support component B), thecomponent A) or A′) and any component C) are combined is immaterial. Thecomponents A) or A′) and C) can be added independently of one another orsimultaneously or in premixed form to B). After the individual processsteps, the solid can be washed with suitable inert solvents such asaliphatic or aromatic hydrocarbons.

In a preferred embodiment the monocyclopentadienyl complex A) or A′) isbrought into contact with the activating compound C) in a suitablesolvent, usually giving a soluble reaction product, an adduct or amixture. The preparation obtained in this way is then brought intocontact with the support B), which may have been pretreated, and thesolvent is completely or partly removed. This preferably gives a solidin the form of a free-flowing powder. Examples of the industrialimplementation of the above process are described in WO 96/00243, WO98/40419 or WO 00/05277. A further preferred embodiment comprisesfirstly applying the activating compound C) to the support B) andsubsequently bringing this supported activating compound into contactwith the monocyclopentadienyl complex A) or A′).

The component D) can likewise be reacted in any order with thecomponents A) or A′) and, if desired, B) and C). For example, themonocyclopentadienyl complex A) can be brought into contact with thecomponent(s) C) and/or D) either before or after being brought intocontact with the olefins to be polymerized. Preactivation using one ormore components C) prior to mixing with the olefin and further additionof the same or different components C) and/or D) after this mixture hasbebg+en brought into contact with the olefin is also possible.Preactivation is generally carried out at 10-100° C., in particular20-80° C.

Preference is given to D) firstly being brought into contact withcomponent C) and then dealing with the components A) or A′) and B) andany further C) as described above. In another preferred embodiment, acatalyst solid is prepared from the components A) or A′), B) and C) asdescribed above and this is brought into contact with the component D)during, at the beginning of or shortly before the polymerization.Preference is given to D) firstly being brought into contact with theα-olefin to be polymerized and the catalyst solid comprising thecomponents A) or A′), B) and C) as described above subsequently beingadded.

It is also possible for the catalyst system firstly to be prepolymerizedwith α-olefins, preferably linear C₂-C₁₀-1-alkenes and in particularethylene or propylene, and the resulting prepolymerized catalyst solidthen to be used in the actual polymerization. The mass ratio of catalystsolid used in the prepolymerization to monomer polymerized onto it isusually in the range from 1:0.1 to 1:1 000, preferably from 1:1 to1:200.

Furthermore, a small amount of an olefin, preferably an α-olefin, forexample vinylcyclohexane, styrene or phenyldimethylvinylsilane, asmodifying component, an antistatic or a suitable inert compound such asa wax or oil can be added as additive during or after the preparation ofthe catalyst system. The molar ratio of additives to transition metalcompound A) or A′) is usually from 1:1 000 to 1 000:1, preferably from1:5 to 20:1.

In the process of the present invention for the copolymerization ofethylene with α-olefins, α-olefins are generally hydrocarbons havingterminal double bonds, with the hydrocarbon also being able to bearfunctional groups containing atoms of groups 14 to 17 of the PeriodicTable of the Elements. Suitable monomers Include functionalizedolefinically unsaturated compounds such as acrolein, esters or amidederivatives of acrylic or methacrylic acid, for example acrylates,methacrylates or acrylonitrile, or vinyl esters, for example vinylacetate. Preference is given to nonpolar olefinic compounds whichcontain only carbon atoms, including aryl-substituted α-olefins.Particularly preferred α-olefins are linear or branchedC₂-C₁₂-1-alkenes, in particular linear C₂-C₁₀-1-alkenes such as ethene,propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene orbranched C₂-C₁₀-1-alkenes such as 4-methyl-1-pentene, conjugated andnonconjugated dienes such as 1,3-butadiene, 1,5hexadiene or1,7-octadiene or vinylaromatic compounds such as styrene or substitutedstyrene. It is also possible to polymerize mixtures of variousα-olefins. Preference is given to polymerizing at least one α-olefinselected from the group consisting of ethene, propene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene and 1-decene.

Mixtures of two or more α-olefins can also be copolymerized with ethene.Preference is given to using monomer mixtures containing at least 50 mol% of ethene.

The process of the present invention for the polymerization of ethylenewith α-olefins can be combined with all industrially knownpolymerization processes at from −60 to 350° C. and pressures of from0.5 to 4 000 bar. The polymerization can be carried out in a knownmanner in bulk, in suspension, in the gas phase or in a supercriticalmedium in the customary reactors used for the polymerization of olefins.It can be carried out batchwise or preferably continuously in one ormore stages. High-pressure polymerization processes in tube reactors orautoclaves, solution processes, suspension processes, stirred gas-phaseprocesses or gas-phase fluidized-bed processes are all possible.

The polymerizations are usually carried out at from −60 to 350° C. underpressures of from 0.5 to 4 000 bar at mean residence times of from 0.5to 5 hours, preferably from 0.5 to 3 hours. The advantageous pressureand temperature ranges for carrying out the polymerizations usuallydepend on the polymerization method. In the case of high-pressurepolymerization processes, which are usually carried out at pressures offrom 1 000 to 4 000 bar, in particular from 2 000 to 3 500 bar, highpolymerization temperatures are generally also set. Advantageoustemperature ranges for these high-pressure polymerization processes arefrom 200 to 320° C., in particular from 220 to 290° C. In the case oflow-pressure polymerization processes, a temperature which is at least afew degrees below the softening temperature of the polymer is generallyset. These polymerization processes are preferably carried out at from50 to 180° C., more preferably from 70 to 120° C. In the case ofsuspension polymerizations, the polymerization is usually carried out ina suspension medium, preferably an inert hydrocarbon such as isobutaneor a mixture of hydrocarbons, or else in the monomers themselves. Thepolymerization temperatures are generally in the range from −20 to 115°C., and the pressure is generally in the range from 1 to 100 bar. Thesolids content of the suspension is generally in the range from 10 to80%. The polymerization can be carried out batchwise, e.g. in stirringautoclaves, or continuously, e.g. in tube reactors, preferably in loopreactors. Particular preference is given to employing the Phillips PFprocess as described in U.S. Pat. No. 3,242,150 and U.S. Pat. No.3,248,179. The gas-phase polymerization is generally carried out at from30 to 125° C. at pressures of from 1 to 50 bar.

Among the abovementioned polymerization processes, particular preferenceis given to gas-phase polymerization, in particular in gas-phasefluidized-bed reactors, solution polymerization and suspensionpolymerization, in particular in loop reactors and stirred tankreactors. The gas-phase polymerization can also be carried out in thecondensed or supercondensed phase, in which part of the circulating gasis cooled to below the dew point and is recirculated as a two-phasemixture to the reactor. It is also possible to use a multizone reactorin which two polymerization zones are linked to one another and thepolymer is passed alternately through these two zones a number of times.The two zones can also have different polymerization conditions. Such areactor is described, for example, in WO 97/04015. The different oridentical polymerization processes can also, if desired, be connected inseries so as to form a polymerization cascade, for example in theHostalen process. A parallel reactor arrangement using two or moreidentical or different processes is also possible. Furthermore, molarmass regulators, for example hydrogen, or customary additives such asantistatics can also be used in the polymerizations.

The ethylene copolymer of the present Invention can also be aconstituent of a polymer mixture. Thus, for example, two or threedifferent ethylene copolymers according to the present invention whichmay differ, for example, in their density and/or their molar massdistribution and/or their short chain branching distribution can bemixed with one another. They can also be produced by means of a cascadepolymerization.

Further useful polymer mixtures comprise

-   (E) from 1 to 99% by weight of one or more of the ethylene    copolymers according to the present invention and-   (F) from 1 to 99% by weight of a polymer which is different from    (E), where the percentages by weight are based on the total mass of    the polymer mixture.

Polymer mixtures comprising

-   (E) from 1 to 99% by weight of one of the ethylene copolymers    according to the present invention, in particular from 30 to 95% by    weight and particularly preferably from 50 to 85% by weight, and-   (F) from 1 to 99% by weight of a polyolefin which is different from    (E), in particular from 5 to 70% by weight and particularly    preferably from 15 to 50% by weight, where the percentages by weight    are based on the total mass of the polymer mixture, are particularly    suitable.

The type of further polymer components (F) in the mixture depends on theintended use of the mixture. The mixture can be obtained, for example,by blending with one or more additional LLDPEs or HDPEs or LDPEs or PPsor polyamides or polyesters. Alternatively, the polymer mixture can beproduced by simultaneous polymerization using a monocyclopentadienylcomplex and one or more catalyst systems which are likewise active inthe polymerization of olefins. Suitable catalysts for producing thepolymer blends or for simultaneous polymerization are, in particular,classical Ziegler-Natta catalysts based on titanium, classical Phillipscatalysts based on chromium oxides, metallocenes, in particularcomplexes of metals of groups 3 to 6 of the Periodic Table of theElements containing one, two or three cyclopentadienyl, indenyl and/orfluorenyl systems, viz. constrained geometry complexes (cf., forexample, EP-A 0 416 815 or EP-A 0 420 436), nickel and palladiumbisimine systems (for their preparation, see WO 9803559 A1) or iron andcobalt pyridinebisimine compounds (for their preparation, see WO 9827124A1). However, in the case of a mixture consisting of various polymersaccording to the present invention, it is also possible to use anotherchromium complex A). The further polymerization catalysts can likewisebe supported on one and the same support or different supports.

The ethylene copolymer of the present invention can also form mixtureshaving a broad or bimodal molar mass distribution with other olefinpolymers, in particular ethylene homopolymers and copolymers. Thesemixtures can be obtained either by means of the above-describedsimultaneous presence of a further catalyst suitable for thepolymerization of olefins or by subsequent blending of the separatelyprepared polymers or copolymers.

The blends comprising olefin copolymers according to the presentinvention can also further comprise two or three other olefin polymersor copolymers. These can be, for example, LDPEs (blends thereof aredescribed, for example, in DE-A1-19745047) or polyethylene homopolymers(blends thereof are described, for example, in EP-B-100843), LLDPEs (asdescribed, for example, in EP-B-728160 or WO-A-90/03414), LLDPE/LDPE (WO95/27005 or EP-B1-662989). The proportion of copolymers according to thepresent invention is at least 40-99% by weight, preferably 50-90% byweight, based on the total mass of the polymer mixture.

The ethylene copolymers, polymer mixtures and blends can furthercomprise known auxiliaries and/or additives such as processingstabilizers, stabilizers against the action of light and heat, customaryadditives such as lubricants, antioxidants, antiblocking agents andantistatics, and also, if desired, colorants. The type and amount ofthese additives are known to those skilled in the art.

Furthermore, it has been found that mixing in small amounts offluoroelastomers or thermoplastic polyesters can give furtherimprovements in the processing properties of the polymers of the presentinvention. Such fluoroelastomers are known as such as processing aidsand are commercially available, e.g. under the trade names Viton® andDynamar® (cf., for example, U.S. Pat. No. 3,125,547). They arepreferably added in amounts of from 10 to 1 000 ppm, particularlypreferably from 20 to 200 ppm, based on the total mass of the polymermixture according to the present invention.

The polymers of the present invention can also be modified subsequentlyby grafting, crosslinking, hydrogenation, functionalization or othermodification reactions known to those skilled in the art.

The production of the polymer blends by mixing can be carried out by allknown methods. It can be achieved, for example, by feeding the powdercomponents into a granulation apparatus, e.g. a twin-screw kneader(ZSK), Farrel kneader or Kobe kneader. It is also possible to process agranulated mixture directly on a film production plant.

The polymers and polymer mixtures of the present invention are veryuseful, for example, for the production of films on blown film and castfilm plants at high outputs. The films made of the polymer mixturesdisplay very good mechanical properties, high shock resistance and hightear strength combined with very good optical properties, in particulartransparency and gloss. They are particularly useful for the packagingsector, for example as heat sealing films, and both for labels and sacksand for the food sector. Furthermore, the films display only a slightblocking tendency and can therefore be passed through machines withoutadditions of lubricants and antiblocking agents or with additions ofonly small amounts thereof.

Owing to their good mechanical properties, the ethylene copolymers ofthe present invention are likewise suitable for the production of fibersand moldings, in particular pipes and crosslinkable pipes. They arelikewise suitable for blow molding, rotomolding or Injection molding.They are also useful as compounding components, bonding agents and asrubber component in polypropylene, in particular in polypropylenecompounds having high Impact toughnesses.

The following examples illustrate the invention.

EXAMPLES

NMR samples were dispensed under inert gas and, if appropriate, meltedin. The solvent signals served as internal standard in the ¹H- and¹³C-NMR spectra, and the chemical shifts were then converted intochemical shifts relative to Tetramethylsilane.

The density [g/cm³] was determined in accordance with ISO 1183.

The determination of the molar mass distributions and the means M_(n),M_(w), and M_(w)/M_(n) derived therefrom was carried out by means ofhigh-temperature gel permeation chromatography using a method based onDIN 55672 under the following conditions: solvent1,2,4-trichlorobenzene, flow: 1 ml/min, temperature: 140° C.,calibration using PE standards.

The TREF analyses were carried out under the following conditions:solvent: 1,2,4-trichlorobenzene, flow: 1 ml/min, healing rate: 1°C./min, amount of polymer: 5-10 mg, support: diatomaceous earth(kieselgur).

The CDBI was determined as described in WO-A-93/03093.

The Crystaf® measurements were carried out on an instrument from PolymerChar, P.O. Box 176, E-46980 Paterna, Spain, using 1,2-dichlorobenzene assolvent and the data were processed using the associated software. TheCrystaf® temperature-time curve is depicted in FIG. 1. The differentialCrystaf® curve shows the modality of the short chain branchingdistribution. To convert the Crystaf® curves obtained into CH₃ groupsper 1 000 carbon atoms, the curve shown in FIG. 2 was used, depending onthe type of comonomer employed. In this curve, the weight averagetemperature T-w is defined as the sum over all proportions by weight m-imultiplied by the temperature T-i, divided by the sum over allproportions by weight m-i:T-w=Σ(m-i·T-i)/Σm-i

The degree of short chain branching (CH₃/1 000 C) can thus be calculatedsimply in accordance with the following equation: (CH₃/1 000 C)=a·T-w+b(see FIG. 2), in which the abbreviations are as follows:

weight average temperature T-w: (° C.) slope a: −0.582 (CH₃/1 000 C)/(°C.) intercept b: 60.46 (CH₃/1 000 C)

The vinyl and vinyliden group content was determined by ¹H-NMR.

The long chain branching rate λ was determined by light scattering asdescribed in ACS Series 521, 1993, Chromatography of Polymers, Ed.Theodore Provder; Simon Pang and Alfred Rudin: Size-ExclusionChromatographic Assessment of Long-Chain Branch Frequency inPolyethylenes, page 254-269.

Abbreviations used in the following table:

Cat. catalyst t(poly) duration of the polymerization polymer amount ofpolymer formed M_(w) weight average molar mass M_(n) number averagemolar mass density polymer density Prod. productivity of the catalyst ing of polymer obtained per mmol of catalyst (chromium complex) used perhour

Example 1 1.1. Preparation of[2-(1H-inden-3-yl)methyl]-3,5,6-trimethylpyrazine

A mixture of 13.6 ml (0.1 mol) of 2,3,5,6-tetramethylpyrazine in 50 mlof tetrahydrofuran was cooled to −20° C. and 62.5 ml of n-butyllithium(1.6M in hexane, 0.1 mol) were subsequently added while stirring. Themixture was allowed to warm to room temperature while stirring. Afterstirring for a further 1 hour, the solution was cooled to −60° C. and asolution of 15 g (0.11 mol) of 1-indanone in 20 ml of tetrahydrofuranwas added over a period of 15 minutes while stirring. The mixture wasallowed to warm to room temperature while stirring and was stirred for afurther 12 hours. The mixture was then hydrolyzed with 250 ml of dilutehydrochloric acid and allowed to stand. After 24 hours, the2-[(2,3-dihydro-1H-inden-1-ylidenemethyl]-3,5,6-trimethylpyrazinehydrochloride (the by-product) which had precipitated was filtered off.The organic phase was separated off from the liquid phases and theaqueous phase was extracted twice with ethyl acetate. The aqueous phasewas then neutralized with aqueous ammonia solution and extracted threetimes with 60 ml each time of methylene chloride. The organic phaseswere combined, dried over magnesium sulfate, the magnesium sulfate wasfiltered off and the solvent was distilled off. This gave 17.3 g of amixture of 2-(1H-inden-3-ylmethyl)pyridine and2-[(E)-2,3-dihydro-1H-inden-1-ylidenemethyl]-3,5,6-bimethylpyrazine (55%yield) and unreacted tetramethylpyrazine in a ratio of 10:3 (NMR). Themixture was used directly in the next step. NMR ¹H (CDCl₃): 7.54 (d,1H); 7.48 (d, 1H); 7.35 (t, 1H); 7.25 (t, 9H); 5.92 (br.s., 1H); 4.07(br.s., 2H); 3.54 (br.s., 2H); 2.56 (s., 3H); 2.54 (s., 3H); 2.52 (s.,3H).

1.2. Preparation of(1-(2-(3,5,6-trimethylpyrazine)methyl)indenyl)chromium dichloride

A solution of 7.25 g of the above mixture in 80 ml of tetrahydrofuranwas cooled to −100° C. While stirring, 16 ml of a 15% strengthn-butyllithium solution in hexane (0.0256 mol) were slowly addeddropwise. After the addition was complete, the reaction mixture wasstirred for a further one hour at −100° C. The mixture was subsequentlyallowed to warm to room temperature. After stirring for a further 2hours, the solution was cooled to −60° C. and 10.2 g (0.0272 mol) ofchromium trichloride tris(tetrahydrofuran) were added while stirring.The mixture was allowed to warm slowly to room temperature and wassubsequently stirred for a further 10 hours at room temperature. Thesolid which had precipitated was filtered off, washed twice with diethylether and dried under reduced pressure. This gave 5.2 g of a greenpowder of which 4.2 g were recrystallized from a mixture of CH₂Cl₂-Et₂O.3.1 g of (1-(2-3,5,6-bimethylpyrazine)methyl)indenyl)chromium dichloride(43%) were obtained.

Example 2 2.1. Preparation of [2-1H-inden-3-yl)-1-methylethyl]pyridine

A solution of 7.25 g (0.046 mol) of 2-bromopyridine in 20 ml of diethylether was cooled to −60° C. and a mixture of 28.7 ml of n-butyllithium(1.6M in hexane, 0.046 mol) and 70 ml of diethyl ether was subsequentlyadded while stirring. The mixture was stirred for a further 15 minutesand a solution of 7.16 g (0.046 mol) of 1-(1-methylethylidene)-1-indenedissolved in 10 ml of ether was then added. The mixture was allowed towarm to room temperature and was hydrolyzed with 100 ml of dilutehydrochloric acid. The organic phase was separated off and the aqueousphase was extracted once with diethyl ether, after which the aqueousphase was neutralized with aqueous ammonia solution and extracted threetimes with 50 ml each time of chloroform. The organic phases werecombined, dried over magnesium sulfate, the magnesium sulfate wasfiltered off and the solvent was distilled off. 0.54 g (5%) of[2-(1H-inden-3-yl)-1-methylethyl]-pyridine was obtained.

2.2. Preparation of (3-(2-pyridyl-1-methylethyl)indenyl)chromiumdichloride

A solution of 0.54 g (0.0023 mol) of[2-1H-inden-3-yl)-1-methylethyl]pyridine in 20 ml of tetrahydrofuran wascooled to −100° C. 1.72 ml of a 15% strength n-butyllithium solution inhexane (0.0027 mol) were slowly added dropwise. After the addition wascomplete, the reaction mixture was stirred at −100° C. for a further 30minutes. The mixture was subsequently allowed to warm to roomtemperature. After stirring for a further 1 hour, the solution wascooled to −60° C. and 1.1 g (0.0029 mol) of chromium trichloridebis(tetrahydrofuran) were added while stirring. The mixture was allowedto warm slowly to room temperature and was subsequently stirred for afurther 10 hours at room temperature. The reaction mixture was thenrefluxed for 20 minutes and subsequently cooled to room temperature. Thesolid which had precipitated was filtered off, washed with diethyl etherand dried under reduced pressure. This gave 0.3 g of(3-(2-pyridyl-1-methylethyl)indenyl)chromium dichloride (37%).

Comparative example 1

5-[(2-Pyridyl)methyl]-1,2,3,4-tetramethylcyclopentadienylchromiumdichloride was prepared as described in WO 01/92346.

Polymerization

The polymerizations were carried out at 40° C. under argon in a 1 lfour-necked flask provided with contact thermometer, stirrer with Teflonblade, heating mantle and gas inlet tube. The appropriate amount of MAO(10% strength solution in toluene, Cr:Al=1:500) was added to a solutionof the amount indicated in table 1 of the respective complex in 250 mlof toluene and the mixture was heated to 40° C. on a water bath.

Shortly before introduction of ethylene, 3 ml of hexene were placed inthe flask and about 20-40 l/h of ethylene were subsequently passedthrough the initial charge at atmospheric pressure. The remaining amountof hexene (7 ml) was introduced via a dropping funnel over a period of15 minutes. After the time indicated in table 1 under a constantethylene flow, the polymerization was stopped by addition of methanolHCl solution (15 ml of concentrated hydrochloric acid in 50 ml ofmethanol). 250 ml of methanol were subsequently added and the whitepolymer formed was filtered off, washed with methanol and dried at 70°C.

TABLE 1 Polymerization results Catalyst from Amount of cat. t(poly)Polymer Prod. M_(w) Density Short chain branching Ex. [mg] [min] [g][g/mmolCr h] [g/mol] M_(w)/M_(n) [g/cm³] CDBI distribution 1 7.4 25 3.8  459 106 743 2.94 0.934 <50% bimodal 2 9.8 20 11.5 1 260 252 011 6.24n.d. <50% bimodal C1 7.7 20 12.8 1 692  28 067 4.61 0.94 >50% monomodal

Example 3

(3-(2-(4-Methylpyridyl)methyl)indenyl)chromium dichloride was preparedby a method analogous to example 1 but using the corresponding amount of2,4-dimethylpyridine in place of tetramethylpyrazine.

The polymerization was carried out as described above at 40° C. underargon using hexene as comonomer and a polymerization time of 60 minutes.The activity of the complex (Cr: MAO=1:500) was 1 730 g/mmol of Cr h.The M_(w) of the copolymer was 283 910 g/mol, the M_(w)/M_(n) was 2.57.The copolymer had a CDBI of less than 50% and a bimodal short chainbranching distribution (differential Crystaf® curve). The maxima of theCrystaf® peaks In the differential Crystaf® curve were at 12° C. and 33°C. The vinyl group content was 0.19 vinyl groups/1000 carbon atoms. Thevinyliden group content was 0.52 vinyliden groups/1000 carbon atoms. Thelong chain branching rate λ less than 0.1 lcb/1000 carbon atoms.

1. A copolymer of ethylene with α-olefins which comprises a molar massdistribution M_(w)/M_(n) of from 1 to 8, a density of from 0.85 to 0.94g/cm³, a number average molar mass M_(n) of from 10,000 g/mol to4,000,000 g/mol, a CDBI of less than 50%, a vinyl group content of from0.1 to 1 vinyl groups/1000 carbon atoms, a Lcb rate of from 0.001 to0.09 Lcb/1000 carbon atoms, the copolymer comprising at least a bimodalshort chain branching distribution, and wherein a side chain branchingof the maxima of the individual peaks of the short chain branchingdistribution, as determined by crystallization analysis fractionation(CRYSTAF), of the copolymer of ethylene and the α-olefins is greaterthan 5 CH₃/1000 carbon atoms.
 2. The copolymer of ethylene withα-olefins as claimed in claim 1, wherein the number average molar massM_(n) is from 150,000 g/mol to 1,000,000 g/mol.
 3. The copolymer ofethylene with α-olefins as claimed in claim 1 which has at least onepeak, as determined by CRYSTAF, of a differential distribution in therange from 15 to 40° C., and at least one further peak, as determined byCRYSTAF, of the differential distribution in the range from 25 to 80° C.4. The copolymer of ethylene with α-olefins as claimed in claim 1,wherein the copolymer of ethylene with α-olefins comprise a trimodalshort chain branching distribution.
 5. A polymer mixture comprising: (E)from 1 to 99% by weight of at least one ethylene copolymer comprising amolar mass distribution M_(w)/M_(n) of from 1 to 8, a density of from0.85 to 0.94 g/cm³, a number average molar mass M_(n) of from 10,000g/mol to 4,000,000 g/mol, a CDBI of less than 50%, a vinyl group contentof from 0.1 to 1 vinyl groups/1000 carbon atoms, a Lcb rate of from0.001 to 0.09 Lcb/1000 carbon atoms, the copolymer comprising at least abimodal short chain branching distribution, and wherein a side chainbranching of the maxima of the individual peaks of the short chainbranching distribution, as determined by crystallization analysisfractionation (CRYSTAF), of the ethylene copolymer is greater than 5CH₃/1000 carbon atoms; and (F) from 1 to 99% by weight of a polymerwhich is different from (E), where the percentages by weight are basedon the total mass of the polymer mixture.
 6. A fiber, film or moldingcomprising an ethylene copolymer comprising a molar mass distributionM_(w)/M_(n) of from 1 to 8, a density of from 0.85 to 0.94 g/cm³, anumber average molar mass M_(n) of from 10,000 g/mol to 4,000,000 g/mol,a CDBI of less than 50%, a vinyl group content of from 0.1 to 1 vinylgroups/1000 carbon atoms, a Lcb rate of from 0.001 to 0.09 Lcb/1000carbon atoms, the copolymer comprising at least a bimodal short chainbranching distribution, and wherein a side chain branching of the maximaof the individual peaks of the short chain branching distribution, asdetermined by crystallization analysis fractionation (CRYSTAF), of theethylene copolymer is greater than 5 CH₃/1000 carbon atoms.